diff --git a/Elwig/Windows/AdministrationWindow.cs b/Elwig/Windows/AdministrationWindow.cs
new file mode 100644
index 0000000..4cc58fb
--- /dev/null
+++ b/Elwig/Windows/AdministrationWindow.cs
@@ -0,0 +1,261 @@
+using Elwig.Helpers;
+using Elwig.Models;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace Elwig.Windows {
+    public abstract class AdministrationWindow : ContextWindow {
+        protected Control[] ExemptInputs { private get; set; }
+        protected Control[] RequiredInputs { private get; set; }
+        private TextBox[] TextBoxInputs;
+        private ComboBox[] ComboBoxInputs;
+        private CheckBox[] CheckBoxInputs;
+        private RadioButton[] RadioButtonInputs;
+        private readonly Dictionary<Control, bool> Valid;
+        private readonly Dictionary<Control, object?> OriginalValues;
+
+        public AdministrationWindow() : base() {
+            ExemptInputs = Array.Empty<Control>();
+            RequiredInputs = Array.Empty<Control>();
+            TextBoxInputs = Array.Empty<TextBox>();
+            ComboBoxInputs = Array.Empty<ComboBox>();
+            CheckBoxInputs = Array.Empty<CheckBox>();
+            RadioButtonInputs = Array.Empty<RadioButton>();
+            Valid = new();
+            OriginalValues = new();
+            Loaded += OnLoaded;
+        }
+
+        private void OnLoaded(object sender, RoutedEventArgs evt) {
+            TextBoxInputs = Utils.FindVisualChilds<TextBox>(this, ExemptInputs).ToArray();
+            ComboBoxInputs = Utils.FindVisualChilds<ComboBox>(this, ExemptInputs).ToArray();
+            CheckBoxInputs = Utils.FindVisualChilds<CheckBox>(this, ExemptInputs).ToArray();
+            RadioButtonInputs = Utils.FindVisualChilds<RadioButton>(this, ExemptInputs).ToArray();
+            foreach (var tb in TextBoxInputs)
+                Valid[tb] = true;
+        }
+
+        abstract protected void UpdateButtons();
+
+        protected void ValidateInput(Control input, bool valid) {
+            Valid[input] = valid;
+        }
+
+        protected bool SenderIsRequired(object sender) {
+            return (sender is Control c) && RequiredInputs.Contains(c);
+        }
+
+        protected void ClearInputStates() {
+            foreach (var tb in TextBoxInputs)
+                Utils.ClearInputState(tb);
+            foreach (var cb in ComboBoxInputs)
+                Utils.ClearInputState(cb);
+            foreach (var cb in CheckBoxInputs)
+                Utils.ClearInputState(cb);
+            foreach (var rb in RadioButtonInputs)
+                Utils.ClearInputState(rb);
+        }
+
+        protected void ValidateRequiredInputs() {
+            foreach (var input in RequiredInputs) {
+                if (input is TextBox tb && tb.Text.Length == 0) {
+                    Utils.SetInputInvalid(input);
+                    Valid[input] = false;
+                } else if (input is ComboBox cb && cb.SelectedItem == null) {
+                    Utils.SetInputInvalid(input);
+                }
+            }
+            foreach (var cb in ComboBoxInputs) {
+                if (cb.ItemsSource != null && cb.SelectedItem == null)
+                    Utils.SetInputInvalid(cb);
+            }
+        }
+
+        protected void LockInputs() {
+            foreach (var tb in TextBoxInputs)
+                tb.IsReadOnly = true;
+            foreach (var cb in ComboBoxInputs)
+                cb.IsEnabled = false;
+            foreach (var cb in CheckBoxInputs)
+                cb.IsEnabled = false;
+            foreach (var rb in RadioButtonInputs)
+                rb.IsEnabled = false;
+        }
+
+        protected void UnlockInputs() {
+            foreach (var tb in TextBoxInputs)
+                tb.IsReadOnly = false;
+            foreach (var cb in ComboBoxInputs)
+                cb.IsEnabled = true;
+            foreach (var cb in CheckBoxInputs)
+                cb.IsEnabled = true;
+            foreach (var rb in RadioButtonInputs)
+                rb.IsEnabled = true;
+        }
+
+        protected void ClearOriginalValues() {
+            OriginalValues.Clear();
+        }
+
+        protected void FillOriginalValues() {
+            foreach (var tb in TextBoxInputs)
+                OriginalValues[tb] = tb.Text;
+            foreach (var cb in ComboBoxInputs)
+                OriginalValues[cb] = cb.SelectedItem;
+            foreach (var cb in CheckBoxInputs)
+                OriginalValues[cb] = (cb.IsChecked ?? false) ? bool.TrueString : null;
+            foreach (var rb in RadioButtonInputs)
+                OriginalValues[rb] = (rb.IsChecked ?? false) ? bool.TrueString : null;
+        }
+
+        protected void ClearInputs() {
+            foreach (var tb in TextBoxInputs)
+                tb.Text = "";
+            foreach (var cb in ComboBoxInputs)
+                cb.SelectedItem = null;
+            foreach (var cb in CheckBoxInputs)
+                cb.IsChecked = false;
+            foreach (var rb in RadioButtonInputs)
+                rb.IsChecked = false;
+            ValidateRequiredInputs();
+        }
+
+        protected bool IsValid() {
+            return Valid.All(kv => kv.Value) && ComboBoxInputs.All(cb => cb.ItemsSource == null || cb.SelectedItem != null);
+        }
+
+        protected bool InputHasChanged(Control input) {
+            if (!OriginalValues.ContainsKey(input)) {
+                return false;
+            } else if (input is TextBox tb) {
+                return OriginalValues[tb]?.ToString() != tb.Text;
+            } else if (input is ComboBox sb) {
+                return OriginalValues[sb] != sb.SelectedItem;
+            } else if (input is CheckBox cb) {
+                return (OriginalValues[cb] != null) != (cb.IsChecked ?? false);
+            } else if (input is RadioButton rb) {
+                return (OriginalValues[rb] != null) != (rb.IsChecked ?? false);
+            } else {
+                return false;
+            }
+        }
+
+        protected bool HasChanged() {
+            return !IsValid() ||
+                TextBoxInputs.Any(InputHasChanged) ||
+                ComboBoxInputs.Any(InputHasChanged) ||
+                CheckBoxInputs.Any(InputHasChanged) ||
+                RadioButtonInputs.Any(InputHasChanged);
+        }
+
+        protected void UpdatePlz(TextBox plzInput, ComboBox ortInput) {
+            if (plzInput.Text.Length == 4) {
+                int plz = int.Parse(plzInput.Text);
+                ortInput.ItemsSource = Context.Postleitzahlen.Where(p => p.Plz == plz).ToHashSet();
+            } else {
+                ortInput.ItemsSource = null;
+            }
+            ortInput.SelectedItem = null;
+            if (ortInput.ItemsSource != null) {
+                Utils.SetInputInvalid(ortInput);
+            } else {
+                Utils.ClearInputState(ortInput);
+            }
+            ValidateInput(plzInput, SenderIsRequired(plzInput) || (ortInput.ItemsSource != null));
+            UpdateButtons();
+        }
+
+        protected void InputTextChanged(TextBox input, Func<TextBox, bool, ValidationResult> checker) {
+            InputTextChanged(input, (tb, required, ctx) => checker(tb, required));
+        }
+
+        protected void InputTextChanged(TextBox input, Func<TextBox, bool, AppDbContext, ValidationResult> checker) {
+            InputTextChanged(input, checker(input, SenderIsRequired(input), Context));
+        }
+
+        protected void InputTextChanged(TextBox input, ValidationResult res) {
+            ValidateInput(input, res.IsValid);
+            if (res.IsValid) {
+                if (InputHasChanged(input)) {
+                    Utils.SetInputChanged(input);
+                } else {
+                    Utils.ClearInputState(input);
+                }
+            } else {
+                Utils.SetInputInvalid(input);
+            }
+            UpdateButtons();
+        }
+
+        protected void InputLostFocus(TextBox input, Func<TextBox, bool, ValidationResult> checker, string? msg = null) {
+            InputLostFocus(input, (tb, requiered, ctx) => checker(tb, requiered), msg);
+        }
+
+        protected void InputLostFocus(TextBox input, Func<TextBox, bool, AppDbContext, ValidationResult> checker, string? msg = null) {
+            InputLostFocus(input, checker(input, SenderIsRequired(input), Context), msg);
+        }
+
+        protected void InputLostFocus(TextBox input, ValidationResult res, string? msg = null) {
+            if (!res.IsValid)
+                MessageBox.Show(res.ErrorContent.ToString(), msg ?? res.ErrorContent.ToString(), MessageBoxButton.OK, MessageBoxImage.Warning);
+        }
+
+        protected void CheckBox_Changed(object sender, RoutedEventArgs evt) {
+            var input = (CheckBox)sender;
+            if (SenderIsRequired(input) && input.IsChecked != true) {
+                Utils.SetInputInvalid(input);
+            } else if (InputHasChanged(input)) {
+                Utils.SetInputChanged(input);
+            } else {
+                Utils.ClearInputState(input);
+            }
+            UpdateButtons();
+        }
+
+        protected void RadioButton_Changed(object sender, RoutedEventArgs evt) {
+            var input = (RadioButton)sender;
+            if (SenderIsRequired(input) && input.IsChecked != true) {
+                Utils.SetInputInvalid(input);
+            } else if (InputHasChanged(input)) {
+                Utils.SetInputChanged(input);
+            } else {
+                Utils.ClearInputState(input);
+            }
+            UpdateButtons();
+        }
+
+        protected void TextBox_TextChanged(object sender, RoutedEventArgs evt) {
+            var input = (TextBox)sender;
+            if (SenderIsRequired(input) && input.Text.Length == 0) {
+                ValidateInput(input, false);
+                Utils.SetInputInvalid(input);
+            } else {
+                ValidateInput(input, true);
+                if (InputHasChanged(input)) {
+                    Utils.SetInputChanged(input);
+                } else {
+                    Utils.ClearInputState(input);
+                }
+            }
+            UpdateButtons();
+        }
+
+        protected void ComboBox_SelectionChanged(object sender, RoutedEventArgs evt) {
+            var input = (ComboBox)sender;
+            if (input.ItemsSource != null && input.SelectedItem == null) {
+                Utils.SetInputInvalid(input);
+            } else if (InputHasChanged(input)) {
+                Utils.SetInputChanged(input);
+            } else {
+                Utils.ClearInputState(input);
+            }
+            UpdateButtons();
+        }
+
+    }
+}
diff --git a/Elwig/Windows/ContextWindow.cs b/Elwig/Windows/ContextWindow.cs
new file mode 100644
index 0000000..7963cc9
--- /dev/null
+++ b/Elwig/Windows/ContextWindow.cs
@@ -0,0 +1,23 @@
+using Elwig.Helpers;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace Elwig.Windows {
+    public abstract class ContextWindow : Window {
+        protected readonly AppDbContext Context;
+
+        public ContextWindow() : base() {
+            Context = new();
+        }
+
+        protected override void OnClosing(CancelEventArgs evt) {
+            Context.Dispose();
+            base.OnClosing(evt);
+        }
+    }
+}
diff --git a/Elwig/Windows/MemberAdminWindow.xaml b/Elwig/Windows/MemberAdminWindow.xaml
index ec1c88f..2e12eb9 100644
--- a/Elwig/Windows/MemberAdminWindow.xaml
+++ b/Elwig/Windows/MemberAdminWindow.xaml
@@ -1,4 +1,4 @@
-<Window x:Class="Elwig.Windows.MemberAdminWindow"
+<local:AdministrationWindow x:Class="Elwig.Windows.MemberAdminWindow"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
@@ -305,4 +305,4 @@
             </Grid>
         </GroupBox>
     </Grid>
-</Window>
+</local:AdministrationWindow>
diff --git a/Elwig/Windows/MemberAdminWindow.xaml.cs b/Elwig/Windows/MemberAdminWindow.xaml.cs
index 84ce8af..0dd62ef 100644
--- a/Elwig/Windows/MemberAdminWindow.xaml.cs
+++ b/Elwig/Windows/MemberAdminWindow.xaml.cs
@@ -13,20 +13,11 @@ using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore.ChangeTracking;
 
 namespace Elwig.Windows {
-    public partial class MemberAdminWindow : Window {
+    public partial class MemberAdminWindow : AdministrationWindow {
         private bool IsEditing = false;
         private bool IsCreating = false;
         private List<string> TextFilter = new();
-        private readonly Control[] ExemptInputs;
-        private readonly Control[] RequiredInputs;
-        private IEnumerable<TextBox> TextBoxInputs = Array.Empty<TextBox>();
-        private IEnumerable<ComboBox> ComboBoxInputs = Array.Empty<ComboBox>();
-        private IEnumerable<CheckBox> CheckBoxInputs = Array.Empty<CheckBox>();
-        private IEnumerable<RadioButton> RadioButtonInputs = Array.Empty<RadioButton>();
-        private readonly Dictionary<Control, bool> Valid = new();
-        private readonly Dictionary<Control, object?> OriginalValues = new();
         private readonly RoutedCommand CtrlF = new();
-        private readonly AppDbContext Context = new();
 
         public MemberAdminWindow() {
             InitializeComponent();
@@ -48,21 +39,6 @@ namespace Elwig.Windows {
             ActiveMemberInput.IsChecked = true;
             BranchInput.ItemsSource = Context.Branches.OrderBy(b => b.Name).ToList();
             DefaultKgInput.ItemsSource = Context.WbKgs.Select(k => k.Kg).OrderBy(k => k.Name).ToList();
-            TextBoxInputs = Utils.FindVisualChilds<TextBox>(this, ExemptInputs).ToList();
-            ComboBoxInputs = Utils.FindVisualChilds<ComboBox>(this, ExemptInputs).ToList();
-            CheckBoxInputs = Utils.FindVisualChilds<CheckBox>(this, ExemptInputs).ToList();
-            RadioButtonInputs = Utils.FindVisualChilds<RadioButton>(this, ExemptInputs).ToList();
-            foreach (var tb in TextBoxInputs)
-                Valid[tb] = true;
-        }
-
-        protected override void OnClosing(CancelEventArgs evt) {
-            Context.Dispose();
-            base.OnClosing(evt);
-        }
-
-        private bool SenderIsRequired(object sender) {
-            return (sender is Control c) && RequiredInputs.Contains(c);
         }
 
         private async Task RefreshMemberList() {
@@ -100,17 +76,6 @@ namespace Elwig.Windows {
             RefreshInputs();
         }
 
-        private void ClearInputStates() {
-            foreach (var tb in TextBoxInputs)
-                Utils.ClearInputState(tb);
-            foreach (var cb in ComboBoxInputs)
-                Utils.ClearInputState(cb);
-            foreach (var cb in CheckBoxInputs)
-                Utils.ClearInputState(cb);
-            foreach (var rb in RadioButtonInputs)
-                Utils.ClearInputState(rb);
-        }
-
         private void RefreshInputs(bool validate = false) {
             ClearInputStates();
             Member m = (Member)MemberList.SelectedItem;
@@ -137,14 +102,7 @@ namespace Elwig.Windows {
             ActiveInput.IsChecked = true;
             ContactPostInput.IsChecked = true;
             FillOriginalValues();
-            foreach (var input in RequiredInputs) {
-                if (input is TextBox tb && tb.Text.Length == 0) {
-                    Utils.SetInputInvalid(input);
-                    Valid[input] = false;
-                } else if (input is ComboBox cb && cb.SelectedItem == null) {
-                    Utils.SetInputInvalid(input);
-                }
-            }
+            ValidateRequiredInputs();
         }
 
         private void MemberList_SelectionChanged(object sender, RoutedEventArgs evt) {
@@ -288,28 +246,6 @@ namespace Elwig.Windows {
             DeleteMemberButton.Visibility = Visibility.Hidden;
         }
 
-        private void LockInputs() {
-            foreach (var tb in TextBoxInputs)
-                tb.IsReadOnly = true;
-            foreach (var cb in ComboBoxInputs)
-                cb.IsEnabled = false;
-            foreach (var cb in CheckBoxInputs)
-                cb.IsEnabled = false;
-            foreach (var rb in RadioButtonInputs)
-                rb.IsEnabled = false;
-        }
-
-        private void UnlockInputs() {
-            foreach (var tb in TextBoxInputs)
-                tb.IsReadOnly = false;
-            foreach (var cb in ComboBoxInputs)
-                cb.IsEnabled = true;
-            foreach (var cb in CheckBoxInputs)
-                cb.IsEnabled = true;
-            foreach (var rb in RadioButtonInputs)
-                rb.IsEnabled = true;
-        }
-
         private void LockSearchInputs() {
             SearchInput.IsEnabled = false;
             ActiveMemberInput.IsEnabled = false;
@@ -386,7 +322,7 @@ namespace Elwig.Windows {
         }
 
         private void FillInputs(Member m) {
-            OriginalValues.Clear();
+            ClearOriginalValues();
 
             MgNrInput.Text = m.MgNr.ToString();
             PredecessorMgNrInput.Text = m.PredecessorMgNr.ToString();
@@ -459,267 +395,122 @@ namespace Elwig.Windows {
             FillOriginalValues();
         }
 
-        private void FillOriginalValues() {
-            foreach (var tb in TextBoxInputs)
-                OriginalValues[tb] = tb.Text;
-            foreach (var cb in ComboBoxInputs)
-                OriginalValues[cb] = cb.SelectedItem;
-            foreach (var cb in CheckBoxInputs)
-                OriginalValues[cb] = (cb.IsChecked ?? false) ? bool.TrueString : null;
-            foreach (var rb in RadioButtonInputs)
-                OriginalValues[rb] = (rb.IsChecked ?? false) ? bool.TrueString : null;
-        }
-
-        private void ClearInputs() {
+        protected void ClearInputs() {
             Menu_Member_SendEmail.IsEnabled = false;
             AreaCommitment.Text = "- m²";
-            OriginalValues.Clear();
-            foreach (var tb in TextBoxInputs) {
-                tb.Text = " ";
-                tb.Text = "";
-            }
-            foreach (var cb in ComboBoxInputs) {
-                cb.SelectedItem = null;
-                if (cb.ItemsSource != null)
-                    Utils.SetInputInvalid(cb);
-            }
-            foreach (var cb in CheckBoxInputs)
-                cb.IsChecked = false;
-            foreach (var rb in RadioButtonInputs)
-                rb.IsChecked = false;
+            ClearOriginalValues();
+            base.ClearInputs();
         }
 
-        private bool IsValid() {
-            return Valid.All(kv => kv.Value) && ComboBoxInputs.All(cb => cb.ItemsSource == null || cb.SelectedItem != null);
-        }
-
-        private void UpdateButtons() {
+        override protected void UpdateButtons() {
             if (!IsEditing && !IsCreating) return;
             bool ch = HasChanged(), v = IsValid();
             ResetButton.IsEnabled = (ch);
             SaveButton.IsEnabled = (v && ch);
         }
 
-        private bool InputHasChanged(Control input) {
-            if (!OriginalValues.ContainsKey(input)) {
-                return false;
-            } else if (input is TextBox tb) {
-                return OriginalValues[tb]?.ToString() != tb.Text;
-            } else if (input is ComboBox sb) {
-                return OriginalValues[sb] != sb.SelectedItem;
-            } else if (input is CheckBox cb) {
-                return (OriginalValues[cb] != null) != (cb.IsChecked ?? false);
-            } else if (input is RadioButton rb) {
-                return (OriginalValues[rb] != null) != (rb.IsChecked ?? false);
-            } else {
-                return false;
-            }
+        protected void InputTextChanged(TextBox input, Func<TextBox, bool, AppDbContext, Member?, ValidationResult> checker) {
+            InputTextChanged(input, checker(input, SenderIsRequired(input), Context, (Member)MemberList.SelectedItem));
         }
 
-        private bool HasChanged() {
-            return !IsValid() ||
-                TextBoxInputs.Any(InputHasChanged) ||
-                ComboBoxInputs.Any(InputHasChanged) ||
-                CheckBoxInputs.Any(InputHasChanged) ||
-                RadioButtonInputs.Any(InputHasChanged);
-        }
-
-        private void UpdatePlz(TextBox plzInput, ComboBox ortInput, bool required) {
-            if (plzInput.Text.Length == 4) {
-                int plz = int.Parse(plzInput.Text);
-                ortInput.ItemsSource = Context.Postleitzahlen.Where(p => p.Plz == plz).ToHashSet();
-            } else {
-                ortInput.ItemsSource = null;
-            }
-            ortInput.SelectedItem = null;
-            if (ortInput.ItemsSource != null) {
-                Utils.SetInputInvalid(ortInput);
-            } else {
-                Utils.ClearInputState(ortInput);
-            }
-            Valid[plzInput] = !required || (ortInput.ItemsSource != null);
-            UpdateButtons();
-        }
-
-        private void InputTextChanged(TextBox input, bool required, Func<TextBox, bool, ValidationResult> checker) {
-            InputTextChanged(input, required, (tb, opt, ctx) => checker(tb, opt));
-        }
-
-        private void InputTextChanged(TextBox input, bool required, Func<TextBox, bool, AppDbContext, ValidationResult> checker) {
-            InputTextChanged(input, required, (tb, opt, ctx, m) => checker(tb, opt, ctx));
-        }
-
-        private void InputTextChanged(TextBox input, bool required, Func<TextBox, bool, AppDbContext, Member, ValidationResult> checker) {
-            var res = checker(input, required, Context, (Member)MemberList.SelectedItem);
-            Valid[input] = res.IsValid;
-            if (res.IsValid) {
-                if (InputHasChanged(input)) {
-                    Utils.SetInputChanged(input);
-                } else {
-                    Utils.ClearInputState(input);
-                }
-            } else {
-                Utils.SetInputInvalid(input);
-            }
-            UpdateButtons();
-        }
-
-        private void InputLostFocus(TextBox input, bool required, Func<TextBox, bool, ValidationResult> checker, string? msg = null) {
-            InputLostFocus(input, required, (tb, required, ctx) => checker(tb, required), msg);
-        }
-
-        private void InputLostFocus(TextBox input, bool required, Func<TextBox, bool, AppDbContext, ValidationResult> checker, string? msg = null) {
-            InputLostFocus(input, required, (tb, required, ctx, m) => checker(tb, required, ctx), msg);
-        }
-
-        private void InputLostFocus(TextBox input, bool required, Func<TextBox, bool, AppDbContext, Member?, ValidationResult> checker, string? msg = null) {
-            var res = checker(input, required, Context, (Member)MemberList.SelectedItem);
-            if (!res.IsValid)
-                MessageBox.Show(res.ErrorContent.ToString(), msg ?? res.ErrorContent.ToString(), MessageBoxButton.OK, MessageBoxImage.Warning);
-        }
-
-        private void CheckBox_Changed(object sender, RoutedEventArgs evt) {
-            var input = (CheckBox)sender;
-            if (InputHasChanged(input)) {
-                Utils.SetInputChanged(input);
-            } else {
-                Utils.ClearInputState(input);
-            }
-            UpdateButtons();
-        }
-
-        private void RadioButton_Changed(object sender, RoutedEventArgs evt) {
-            var input = (RadioButton)sender;
-            if (InputHasChanged(input)) {
-                Utils.SetInputChanged(input);
-            } else {
-                Utils.ClearInputState(input);
-            }
-            UpdateButtons();
-        }
-
-        private void TextBox_TextChanged(object sender, RoutedEventArgs evt) {
-            var input = (TextBox)sender;
-            if (SenderIsRequired(input) && input.Text.Length == 0) {
-                Valid[input] = false;
-                Utils.SetInputInvalid(input);
-            } else {
-                Valid[input] = true;
-                if (InputHasChanged(input)) {
-                    Utils.SetInputChanged(input);
-                } else {
-                    Utils.ClearInputState(input);
-                }
-            }
-            UpdateButtons();
-        }
-
-        private void ComboBox_SelectionChanged(object sender, RoutedEventArgs evt) {
-            var input = (ComboBox)sender;
-            if (input.ItemsSource != null && input.SelectedItem == null) {
-                Utils.SetInputInvalid(input);
-            } else if (InputHasChanged(input)) {
-                Utils.SetInputChanged(input);
-            } else {
-                Utils.ClearInputState(input);
-            }
-            UpdateButtons();
+        protected void InputLostFocus(TextBox input, Func<TextBox, bool, AppDbContext, Member?, ValidationResult> checker, string? msg = null) {
+            InputLostFocus(input, checker(input, SenderIsRequired(input), Context, (Member)MemberList.SelectedItem), msg);
         }
 
         private void NumericInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckNumeric);
+            InputTextChanged((TextBox)sender, Validator.CheckNumeric);
         }
 
         private void MgNrInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckMgNr);
+            InputTextChanged((TextBox)sender, Validator.CheckMgNr);
         }
 
         private void MgNrInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckMgNr);
+            InputLostFocus((TextBox)sender, Validator.CheckMgNr);
         }
 
         private void PredecessorMgNrInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckPredecessorMgNr);
+            InputTextChanged((TextBox)sender, Validator.CheckPredecessorMgNr);
         }
 
         private void PredecessorMgNrInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckPredecessorMgNr);
+            InputLostFocus((TextBox)sender, Validator.CheckPredecessorMgNr);
         }
 
         private void BirthdayInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckPartialDate);
+            InputTextChanged((TextBox)sender, Validator.CheckPartialDate);
         }
 
         private void PlzInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckPlz);
-            UpdatePlz((TextBox)sender, OrtInput, SenderIsRequired(sender));
+            InputTextChanged((TextBox)sender, Validator.CheckPlz);
+            UpdatePlz((TextBox)sender, OrtInput);
         }
 
         private void PlzInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckPlz);
-            UpdatePlz((TextBox)sender, OrtInput, SenderIsRequired(sender));
+            InputLostFocus((TextBox)sender, Validator.CheckPlz);
+            UpdatePlz((TextBox)sender, OrtInput);
         }
 
         private void PhoneNrInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckPhoneNumber);
+            InputTextChanged((TextBox)sender, Validator.CheckPhoneNumber);
         }
 
         private void PhoneNrInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckPhoneNumber);
+            InputLostFocus((TextBox)sender, Validator.CheckPhoneNumber);
         }
 
         private void EmailInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckEmailAddress);
+            InputTextChanged((TextBox)sender, Validator.CheckEmailAddress);
         }
 
         private void EmailInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckEmailAddress);
+            InputLostFocus((TextBox)sender, Validator.CheckEmailAddress);
         }
 
         private void IbanInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckIban);
+            InputTextChanged((TextBox)sender, Validator.CheckIban);
         }
 
         private void IbanInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckIban);
+            InputLostFocus((TextBox)sender, Validator.CheckIban);
         }
 
         private void BicInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckBic);
+            InputTextChanged((TextBox)sender, Validator.CheckBic);
         }
 
         private void BicInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckBic);
+            InputLostFocus((TextBox)sender, Validator.CheckBic);
         }
 
         private void UstIdInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckUstId);
+            InputTextChanged((TextBox)sender, Validator.CheckUstId);
         }
 
         private void UstIdInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckUstId);
+            InputLostFocus((TextBox)sender, Validator.CheckUstId);
         }
 
         private void LfbisNrInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckLfbisNr);
+            InputTextChanged((TextBox)sender, Validator.CheckLfbisNr);
         }
 
         private void LfbisNrInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckLfbisNr);
+            InputLostFocus((TextBox)sender, Validator.CheckLfbisNr);
         }
 
         private void BillingPlzInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckPlz);
-            UpdatePlz((TextBox)sender, BillingOrtInput, SenderIsRequired(sender));
+            InputTextChanged((TextBox)sender, Validator.CheckPlz);
+            UpdatePlz((TextBox)sender, BillingOrtInput);
         }
 
         private void BillingPlzInput_LostFocus(object sender, RoutedEventArgs evt) {
-            InputLostFocus((TextBox)sender, SenderIsRequired(sender), Validator.CheckPlz);
-            UpdatePlz((TextBox)sender, BillingOrtInput, SenderIsRequired(sender));
+            InputLostFocus((TextBox)sender, Validator.CheckPlz);
+            UpdatePlz((TextBox)sender, BillingOrtInput);
         }
 
         private void DateInput_TextChanged(object sender, RoutedEventArgs evt) {
-            InputTextChanged((TextBox)sender, SenderIsRequired(sender), Validator.CheckDate);
+            InputTextChanged((TextBox)sender, Validator.CheckDate);
         }
     }
 }