BillLines can be edited now.

prs.desktop/Panels/Suppliers/Bills/SupplierBillLineGrid.cs

@@ -48,7 +48,6 @@ public class SupplierBillLineGrid : DynamicOneToManyGrid<Bill, BillLine>
         base.DoReconfigure(options);
         options
             .BeginUpdate()
-            .Clear()
             .Add(DynamicGridOption.AddRows)
             .Add(DynamicGridOption.DeleteRows)
             .Add(DynamicGridOption.SelectColumns)