Is there a way to RESTRICT a condition in the product attribute selections?

Hello:

We have a product that has a series of conditions when selected. That is, it needs to be programmed and it depends on the customer requirements. If customer elects

- option A then there are like 4 field boxes that open (product attribute conditions we have set for option A )
- option B then there are like 6 field boxes that open (product attribute conditions we have set for option B)

The page looks messy with all these fields open. We would like a cleaner presentation.

So, I tried setting the default field in the first box to " Select xxx " in a drop down. When customer selects ANY other field then the corresponding boxes/fields open up.

This is great except what if the customer does not select any other field??? Customer can checkout without anything selected.

Is there a way to be unable to checkout unless ANY OTHER field with the exception of " Select xxx " is selected?

Thanks,