As a follow up to this post: Stacking Enabled/Disabled States
I am going to show you a working example.
So now when combobox selected index changes it disables and clears all the form fields AFTER textbox1 (so textbox2, and button1)
Additionally you could set up a similar situation for adding data to comboboxes. If you enter in some data and move to the next field, you could call the same thing and have function pointers for the data on the "next" item in the list (so instead of pointing to 2 down you point to 1 down the list).
Good luck and do you have any tips for Ordered Entry of Form data?