How is about your db, Nifty? can you remove the button "Edit combo list" and open formC from combobox?
I have a class module that works with forms and subforms. In this particular case, because you are calling the form from within the combo box via the "List Edit" and not as an event generated by the combo box, then the code failed because it relies on Screen.ActiveControl. I'm not sure I can fix it. But in any case
@moke123 has provided with you with an excellent solution. I would go with that if I were you!