AreaComAdminWindow: Allow users to create new reeds inline

Elwig/Windows/DeliveryAdminWindow.xaml.cs

@@ -19,8 +19,10 @@ using Xceed.Wpf.Toolkit.Primitives;
 namespace Elwig.Windows {
     public partial class DeliveryAdminWindow : AdministrationWindow {
 
+        public readonly bool IsReceipt = false;
+        public int? MgNr => Member?.MgNr;
+
         private bool IsUpdatingGradation = false;
-        private readonly bool IsReceipt = false;
         private Member? Member = null;
         private readonly DispatcherTimer Timer;
         private List<string> TextFilter = new();