diff --git a/Elwig/Dialogs/AbwertenDialog.xaml b/Elwig/Dialogs/AbwertenDialog.xaml
new file mode 100644
index 0000000..cf81046
--- /dev/null
+++ b/Elwig/Dialogs/AbwertenDialog.xaml
@@ -0,0 +1,56 @@
+<Window x:Class="Elwig.Dialogs.AbwertenDialog"
+        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"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:Elwig.Dialogs"
+        mc:Ignorable="d"
+        ResizeMode="NoResize"
+        ShowInTaskbar="False"
+        Topmost="True"
+        WindowStartupLocation="CenterOwner"
+        FocusManager.FocusedElement="{Binding ElementName=WeightInput}"
+        Title="Abwerten" Height="190" Width="400">
+    <Window.Resources>
+        <Style TargetType="Label">
+            <Setter Property="HorizontalAlignment" Value="Left"/>
+            <Setter Property="VerticalAlignment" Value="Top"/>
+            <Setter Property="Padding" Value="2,4,2,4"/>
+            <Setter Property="Height" Value="25"/>
+        </Style>
+        <Style TargetType="TextBox">
+            <Setter Property="HorizontalAlignment" Value="Stretch"/>
+            <Setter Property="VerticalAlignment" Value="Top"/>
+            <Setter Property="FontSize" Value="14"/>
+            <Setter Property="Padding" Value="2"/>
+            <Setter Property="Height" Value="25"/>
+            <Setter Property="TextWrapping" Value="NoWrap"/>
+        </Style>
+        <Style TargetType="Button">
+            <Setter Property="HorizontalAlignment" Value="Right"/>
+            <Setter Property="VerticalAlignment" Value="Bottom"/>
+            <Setter Property="Width" Value="100"/>
+            <Setter Property="Height" Value="25"/>
+        </Style>
+    </Window.Resources>
+    <Grid>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="70"/>
+            <ColumnDefinition/>
+        </Grid.ColumnDefinitions>
+
+        <TextBlock x:Name="Text" Margin="10,10,10,10" Grid.ColumnSpan="2" TextWrapping="Wrap" TextAlignment="Center"
+                   Text="Welche Menge der Lieferung soll abgewertet werden?"/>
+
+        <Label Content="Gewicht:" Margin="10,70,10,10"/>
+        <Grid Grid.Column="1" Width="70" Height="25" Margin="0,70,10,10" HorizontalAlignment="Left" VerticalAlignment="Top">
+            <TextBox x:Name="WeightInput" TextAlignment="Right" Padding="2,2,17,2"
+                     TextChanged="WeightInput_TextChanged"/>
+            <Label Content="kg" Margin="0,4,3,0" HorizontalAlignment="Right" FontSize="10" Padding="2,4,2,4"/>
+        </Grid>
+
+        <Button x:Name="ConfirmButton" Content="Bestätigen" Margin="10,10,115,10" Grid.Column="1" IsEnabled="False" IsDefault="True"
+                Click="ConfirmButton_Click"/>
+        <Button x:Name="CancelButton" Content="Abbrechen" Margin="10,10,10,10" Grid.Column="1" IsCancel="True"/>
+    </Grid>
+</Window>
diff --git a/Elwig/Dialogs/AbwertenDialog.xaml.cs b/Elwig/Dialogs/AbwertenDialog.xaml.cs
new file mode 100644
index 0000000..34086d2
--- /dev/null
+++ b/Elwig/Dialogs/AbwertenDialog.xaml.cs
@@ -0,0 +1,40 @@
+using Elwig.Helpers;
+using System.Text.RegularExpressions;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+
+namespace Elwig.Dialogs {
+    public partial class AbwertenDialog : Window {
+
+        public int Weight;
+
+        public AbwertenDialog(string lsnr, string name, int weight) {
+            Weight = weight;
+            InitializeComponent();
+            Text.Inlines.Clear();
+            Text.Inlines.Add("Welche Menge der Teillieferung ");
+            Text.Inlines.Add(new Run(lsnr) { FontWeight = FontWeights.Bold });
+            Text.Inlines.Add("\nvon ");
+            Text.Inlines.Add(new Run(name) { FontWeight = FontWeights.Bold });
+            Text.Inlines.Add("\nmit ");
+            Text.Inlines.Add(new Run($"{weight:N0}\u202fkg") { FontWeight = FontWeights.Bold });
+            Text.Inlines.Add(" soll abgewertet werden?");
+        }
+
+        private void ConfirmButton_Click(object sender, RoutedEventArgs evt) {
+            DialogResult = true;
+            Weight = int.Parse(WeightInput.Text);
+            Close();
+        }
+
+        private void UpdateButtons() {
+            ConfirmButton.IsEnabled = int.TryParse(WeightInput.Text, out var w) && w > 0 && w <= Weight;
+        }
+
+        private void WeightInput_TextChanged(object sender, TextChangedEventArgs evt) {
+            Validator.CheckInteger(WeightInput, true, 5);
+            UpdateButtons();
+        }
+    }
+}
diff --git a/Elwig/Dialogs/ManualWeighingDialog.xaml.cs b/Elwig/Dialogs/ManualWeighingDialog.xaml.cs
index 9c33f6d..a567b5c 100644
--- a/Elwig/Dialogs/ManualWeighingDialog.xaml.cs
+++ b/Elwig/Dialogs/ManualWeighingDialog.xaml.cs
@@ -15,7 +15,7 @@ namespace Elwig.Dialogs {
 
         private void ConfirmButton_Click(object sender, RoutedEventArgs evt) {
             DialogResult = true;
-            Weight = int.Parse(WeightInput.Text.Replace("\u202f", ""));
+            Weight = int.Parse(WeightInput.Text);
             Reason = Regex.Replace(ReasonInput.Text, @"\s+", "").Trim();
             if (Reason == "") {
                 Reason = null;
diff --git a/Elwig/Helpers/AppDbContext.cs b/Elwig/Helpers/AppDbContext.cs
index 728cddf..a9dc8b0 100644
--- a/Elwig/Helpers/AppDbContext.cs
+++ b/Elwig/Helpers/AppDbContext.cs
@@ -8,6 +8,7 @@ using System.Windows;
 using Microsoft.Extensions.Logging;
 using Microsoft.Data.Sqlite;
 using System.Text.RegularExpressions;
+using System.Collections.Generic;
 
 namespace Elwig.Helpers {
     public class AppDbContext : DbContext {
@@ -157,5 +158,49 @@ namespace Elwig.Helpers {
                 .OrderBy(q => q.MinKmw)
                 .LastOrDefaultAsync();
         }
+
+        public async Task UpdateDeliveryPartAttributes(DeliveryPart part, IEnumerable<WineAttr> attributes) {
+            foreach (var a in attributes) {
+                var attr = part.PartAttributes.Where(pa => pa.AttrId == a.AttrId).FirstOrDefault();
+                if (attributes.Contains(a)) {
+                    DeliveryPartAttr dpa = attr ?? this.CreateProxy<DeliveryPartAttr>();
+                    dpa.Year = part.Year;
+                    dpa.DId = part.DId;
+                    dpa.DPNr = part.DPNr;
+                    dpa.AttrId = a.AttrId;
+                    if (attr == null) {
+                        await AddAsync(dpa);
+                    } else {
+                        Update(dpa);
+                    }
+                } else {
+                    if (attr != null) {
+                        Remove(attr);
+                    }
+                }
+            }
+        }
+
+        public async Task UpdateDeliveryPartModifiers(DeliveryPart part, IEnumerable<Modifier> modifiers) {
+            foreach (var m in modifiers) {
+                var mod = part.PartModifiers.Where(pa => pa.ModId == m.ModId).FirstOrDefault();
+                if (modifiers.Contains(m)) {
+                    DeliveryPartModifier dpm = mod ?? this.CreateProxy<DeliveryPartModifier>();
+                    dpm.Year = part.Year;
+                    dpm.DId = part.DId;
+                    dpm.DPNr = part.DPNr;
+                    dpm.ModId = m.ModId;
+                    if (mod == null) {
+                        await AddAsync(dpm);
+                    } else {
+                        Update(dpm);
+                    }
+                } else {
+                    if (mod != null) {
+                        Remove(mod);
+                    }
+                }
+            }
+        }
     }
 }
diff --git a/Elwig/Helpers/ControlUtils.cs b/Elwig/Helpers/ControlUtils.cs
index ee66310..c74190b 100644
--- a/Elwig/Helpers/ControlUtils.cs
+++ b/Elwig/Helpers/ControlUtils.cs
@@ -106,6 +106,7 @@ namespace Elwig.Helpers {
             var selectedIds = selector.SelectedItems.Cast<object>().Select(i => getId(i)).ToList();
             selector.ItemsSource = source;
             if (source != null) {
+                selector.SelectedItems.Clear();
                 foreach (var i in source.Cast<object>().Where(i => selectedIds.Contains(getId(i))))
                     selector.SelectedItems.Add(i);
             }
diff --git a/Elwig/Helpers/Utils.cs b/Elwig/Helpers/Utils.cs
index 54e6cf6..65bf710 100644
--- a/Elwig/Helpers/Utils.cs
+++ b/Elwig/Helpers/Utils.cs
@@ -213,6 +213,11 @@ namespace Elwig.Helpers {
             return d.ShowDialog() == true ? (d.Weight, d.Reason) : null;
         }
 
+        public static int? ShowAbwertenDialog(string lsnr, string name, int weight) {
+            var d = new AbwertenDialog(lsnr, name, weight);
+            return d.ShowDialog() == true ? d.Weight : null;
+        }
+
         public static Footer GenerateFooter(string lineBreak, string seperator) {
             return new Footer(lineBreak, seperator);
         }
diff --git a/Elwig/Windows/DeliveryAdminWindow.xaml.cs b/Elwig/Windows/DeliveryAdminWindow.xaml.cs
index 052b1e7..5be3bd6 100644
--- a/Elwig/Windows/DeliveryAdminWindow.xaml.cs
+++ b/Elwig/Windows/DeliveryAdminWindow.xaml.cs
@@ -396,8 +396,9 @@ namespace Elwig.Windows {
             kgList.Insert(0, new NullItem());
             ControlUtils.RenewItemsSource(WineKgInput, kgList, i => (i as AT_Kg)?.KgNr);
             UpdateRdInput();
-
             if (IsCreating) await UpdateLsNr();
+
+            await RefreshDeliveryParts();
         }
 
         private void FocusSearchInput(object sender, RoutedEventArgs evt) {
@@ -407,12 +408,12 @@ namespace Elwig.Windows {
             }
         }
 
-        private void RefreshDeliveryParts() {
+        private async Task RefreshDeliveryParts() {
             if (DeliveryList.SelectedItem is Delivery d) {
-                ControlUtils.RenewItemsSource(ModifiersInput, Context.Modifiers.Where(m => m.Year == d.Year).OrderBy(m => m.Ordering).ToList(), i => (i as Modifier)?.ModId);
+                ControlUtils.RenewItemsSource(ModifiersInput, await Context.Modifiers.Where(m => m.Year == d.Year).OrderBy(m => m.Ordering).ToListAsync(), i => (i as Modifier)?.ModId);
                 ControlUtils.RenewItemsSource(DeliveryPartList, d.Parts.OrderBy(p => p.DPNr).ToList(), i => ((i as DeliveryPart)?.Year, (i as DeliveryPart)?.DId, (i as DeliveryPart)?.DPNr), DeliveryPartList_SelectionChanged, ControlUtils.RenewSourceDefault.First);
             } else {
-                ControlUtils.RenewItemsSource(ModifiersInput, Context.Modifiers.Where(m => m.Year == Utils.CurrentLastSeason).OrderBy(m => m.Ordering).ToList(), i => (i as Modifier)?.ModId);
+                ControlUtils.RenewItemsSource(ModifiersInput, await Context.Modifiers.Where(m => m.Year == Utils.CurrentLastSeason).OrderBy(m => m.Ordering).ToListAsync(), i => (i as Modifier)?.ModId);
                 DeliveryPartList.ItemsSource = null;
             }
         }
@@ -550,45 +551,8 @@ namespace Elwig.Windows {
                     pEntry = partNew ? await Context.AddAsync(p) : Context.Update(p);
                 }
 
-                foreach (var a in AttributesInput.ItemsSource.Cast<WineAttr>()) {
-                    var attr = p.PartAttributes.Where(pa => pa.AttrId == a.AttrId).FirstOrDefault();
-                    if (AttributesInput.SelectedItems.Contains(a)) {
-                        DeliveryPartAttr dpa = attr ?? Context.CreateProxy<DeliveryPartAttr>();
-                        dpa.Year = year;
-                        dpa.DId = did;
-                        dpa.DPNr = dpnr;
-                        dpa.AttrId = a.AttrId;
-                        if (attr == null) {
-                            await Context.AddAsync(dpa);
-                        } else {
-                            Context.Update(dpa);
-                        }
-                    } else {
-                        if (attr != null) {
-                            Context.Remove(attr);
-                        }
-                    }
-                }
-
-                foreach (var m in ModifiersInput.ItemsSource.Cast<Modifier>()) {
-                    var mod = p.PartModifiers.Where(pa => pa.ModId == m.ModId).FirstOrDefault();
-                    if (ModifiersInput.SelectedItems.Contains(m)) {
-                        DeliveryPartModifier dpm = mod ?? Context.CreateProxy<DeliveryPartModifier>();
-                        dpm.Year = year;
-                        dpm.DId = did;
-                        dpm.DPNr = dpnr;
-                        dpm.ModId = m.ModId;
-                        if (mod == null) {
-                            await Context.AddAsync(dpm);
-                        } else {
-                            Context.Update(dpm);
-                        }
-                    } else {
-                        if (mod != null) {
-                            Context.Remove(mod);
-                        }
-                    }
-                }
+                await Context.UpdateDeliveryPartAttributes(p, AttributesInput.ItemsSource.Cast<WineAttr>());
+                await Context.UpdateDeliveryPartModifiers(p, ModifiersInput.ItemsSource.Cast<Modifier>());
 
                 await Context.SaveChangesAsync();
             } catch (Exception exc) {
@@ -674,8 +638,8 @@ namespace Elwig.Windows {
             await RefreshDeliveryListQuery();
         }
 
-        private void DeliveryList_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
-            RefreshDeliveryParts();
+        private async void DeliveryList_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
+            await RefreshDeliveryParts();
             if (DeliveryList.SelectedItem != null) {
                 DeleteDeliveryButton.IsEnabled = true;
                 Menu_Print_ShowDeliveryNote.IsEnabled = !IsEditing && !IsCreating;
@@ -689,8 +653,8 @@ namespace Elwig.Windows {
 
         private void DeliveryPartList_SelectionChanged(object? sender, SelectionChangedEventArgs? evt) {
             RefreshInputs();
-            if (DeliveryPartList.SelectedItem != null) {
-                AbwertenButton.IsEnabled = true;
+            if (DeliveryPartList.SelectedItem is DeliveryPart p) {
+                AbwertenButton.IsEnabled = p.QualId != "WEI";
                 EditDeliveryButton.IsEnabled = true;
                 ExtractDeliveryPartButton.IsEnabled = !IsCreating;
                 DeleteDeliveryPartButton.IsEnabled = DeliveryList.SelectedItem is Delivery { Parts.Count: > 1 } && !IsCreating;
@@ -729,7 +693,7 @@ namespace Elwig.Windows {
             DeliveryPartList.IsEnabled = false;
             var p = await UpdateDeliveryPart(DeliveryList.SelectedItem as Delivery, DeliveryPartList.SelectedItem as DeliveryPart);
             await RefreshDeliveryList();
-            RefreshDeliveryParts();
+            await RefreshDeliveryParts();
             DeliveryList.SelectedItem = p?.Delivery;
             DeliveryPartList.SelectedItem = null;
             InitialInputs();
@@ -739,7 +703,7 @@ namespace Elwig.Windows {
             DeliveryPartList.IsEnabled = false;
             var p = await UpdateDeliveryPart(DeliveryList.SelectedItem as Delivery, DeliveryPartList.SelectedItem as DeliveryPart);
             await RefreshDeliveryList();
-            RefreshDeliveryParts();
+            await RefreshDeliveryParts();
             if (p?.Delivery != null) {
                 using var doc = new DeliveryNote(p.Delivery);
                 await doc.Generate();
@@ -786,8 +750,52 @@ namespace Elwig.Windows {
             LockSearchInputs();
         }
 
-        private void AbwertenButton_Click(object sender, RoutedEventArgs evt) {
-            // TODO abwerten dialog
+        private async void AbwertenButton_Click(object sender, RoutedEventArgs evt) {
+            if (DeliveryPartList.SelectedItem is not DeliveryPart p) return;
+            var res = Utils.ShowAbwertenDialog($"{p.Delivery.LsNr}/{p.DPNr}", p.Delivery.Member.AdministrativeName, p.Weight);
+            EntityEntry<DeliveryPart>? entry1 = null, entry2 = null;
+            try {
+                if (res == null || res <= 0)
+                    return;
+                ClearOriginalValues();
+                if (res >= p.Weight) {
+                    ControlUtils.SelectComboBoxItem(WineQualityLevelInput, q => (q as WineQualLevel)?.QualId, "WEI");
+                    ControlUtils.SelectComboBoxItem(WineOriginInput, o => (o as WineOrigin)?.HkId, "OEST");
+                    p.QualId = "WEI";
+                    p.HkId = "OEST";
+                    entry1 = Context.Update(p);
+                } else {
+                    var w = p.Weight - res.Value;
+                    WeightInput.Text = $"{w:N0}";
+                    p.Weight = w;
+                    entry1 = Context.Update(p);
+
+                    var d = p.Delivery;
+                    var p2 = Context.CreateProxy<DeliveryPart>();
+                    var values = Context.Entry(p).CurrentValues;
+                    Context.Entry(p2).CurrentValues.SetValues(values);
+                    p2.DPNr = await Context.NextDPNr(d.Year, d.DId);
+                    p2.Weight = res.Value;
+                    p2.QualId = "WEI";
+                    p2.HkId = "OEST";
+                    entry2 = await Context.AddAsync(p2);
+
+                    await Context.UpdateDeliveryPartAttributes(p2, p.Attributes);
+                    await Context.UpdateDeliveryPartModifiers(p2, p.Modifiers);
+                }
+                await Context.SaveChangesAsync();
+                await RefreshDeliveryParts();
+                FinishInputFilling();
+            } catch (Exception exc) {
+                if (entry1 != null) await entry1.ReloadAsync();
+                if (entry2 != null) {
+                    await entry2.ReloadAsync();
+                    entry2.State = EntityState.Detached;
+                }
+                var str = "Der Eintrag konnte nicht in der Datenbank aktualisiert werden!\n\n" + exc.Message;
+                if (exc.InnerException != null) str += "\n\n" + exc.InnerException.Message;
+                MessageBox.Show(str, "Lieferung aktualisieren", MessageBoxButton.OK, MessageBoxImage.Error);
+            }
         }
 
         private void WeighingManualButton_Click(object sender, RoutedEventArgs evt) {
@@ -829,7 +837,7 @@ namespace Elwig.Windows {
                 Context.Remove(d);
                 await Context.SaveChangesAsync();
                 await RefreshDeliveryList();
-                RefreshDeliveryParts();
+                await RefreshDeliveryParts();
             }
         }
 
@@ -847,10 +855,10 @@ namespace Elwig.Windows {
             UnlockSearchInputs();
             FinishInputFilling();
             await RefreshDeliveryList();
-            RefreshDeliveryParts();
+            await RefreshDeliveryParts();
             RefreshInputs();
 
-            AbwertenButton.IsEnabled = true;
+            AbwertenButton.IsEnabled = p.QualId != "WEI";
             ExtractDeliveryPartButton.IsEnabled = DeliveryPartList.SelectedItem != null && !IsCreating;
             DeleteDeliveryPartButton.IsEnabled = DeliveryList.SelectedItem is Delivery { Parts.Count: > 1 } && !IsCreating;
         }
@@ -877,7 +885,7 @@ namespace Elwig.Windows {
             LockInputs();
             UnlockSearchInputs();
 
-            AbwertenButton.IsEnabled = DeliveryPartList.SelectedItem != null;
+            AbwertenButton.IsEnabled = DeliveryPartList.SelectedItem is DeliveryPart p && p.QualId != "WEI";
             ExtractDeliveryPartButton.IsEnabled = DeliveryPartList.SelectedItem != null && !IsCreating;
             DeleteDeliveryPartButton.IsEnabled = DeliveryList.SelectedItem is Delivery { Parts.Count: > 1 } && !IsCreating;
         }
@@ -896,7 +904,7 @@ namespace Elwig.Windows {
             if (r == MessageBoxResult.Yes) {
                 Context.Remove(p);
                 await Context.SaveChangesAsync();
-                RefreshDeliveryParts();
+                await RefreshDeliveryParts();
             }
         }
 
@@ -920,7 +928,7 @@ namespace Elwig.Windows {
 
         private void ShowNewEditDeleteButtons() {
             NewDeliveryButton.IsEnabled = IsReceipt;
-            AbwertenButton.IsEnabled = DeliveryPartList.SelectedItem != null;
+            AbwertenButton.IsEnabled = DeliveryPartList.SelectedItem is DeliveryPart p && p.QualId == "WEI";
             EditDeliveryButton.IsEnabled = DeliveryPartList.SelectedItem != null;
             DeleteDeliveryButton.IsEnabled = DeliveryList.SelectedItem != null;
             NewDeliveryButton.Visibility = IsReceipt ? Visibility.Visible : Visibility.Hidden;