Bonnie,

It seems like the salesperson_combobox.DataSource = salespersontable wants to control the position in customertable.Rows[]

The only solution that works is setting salesperson_combobox.BindingContext = new BindingContext() but I do not know what else this will affect.

When I do this, the combobox works, the customertable.Rows[] are properly updated (even with the correct salesperson_combobox.ValueMember)!

What affect would there be by adding a new BindingContext() to every combobox or listbox on every form? I do not do binding navigation, I just bind for data (control to Row[]).