Why do you need popup forms? Why not have the comboboxes in the main form and bind them to the fields in the table?
Well, the series of popups will be defined by the user. I'm designing a structure that will point to different popup forms depending on the input from the last. In actuality, I'll have more like 15 popup forms (If user selects A in popup1, it will go to popup5. If I select B in popup 5, I will go to popup 8, etc.). Does that make sense?