Update:

Every document I have with a number of Active X Controls (Option Buttons mainly) is a big headache taking very long time to open !

I came across this nice solution MakeCheckBoxesExclusive macro to make checkboxes behave like Option Buttons.

I tested it on the previously attached doc sample and worked fine (I kept the table and inserted frames in each row and still worked fine).

However, the ShadeCells macro does not work anymore for it needs to first be tweaked to work with the checkboxes now instead of the OBs and, second, it needs the document be unprotected while the MakeCheckBoxesExclusive macro needs it protected to work !