[#15] MailWindow: Add Rundschreiben-Funktion

Elwig/Models/Entities/WbKg.cs

@@ -20,6 +20,9 @@ namespace Elwig.Models.Entities {
         [InverseProperty("Kg")]
         public virtual ISet<WbRd> Rds { get; private set; }
 
+        [InverseProperty("DefaultWbKg")]
+        public virtual ISet<Member> Members { get; private set; }
+
         [NotMapped]
         public WbGem Gem => AtKg.Gem.WbGem;