Preventing certain product cominations in shopping cart

[mushydepot]

I am trying to figure out how to prevent a customer from adding certain products to their shopping cart if they already have another certain product in their cart. For example, if I have products A,B, and C. If product A is already in their cart, I want to be to prevent them from adding products B and C. If that is not possible, is there a way to automatically separate their order into 2 orders, if they have both product A and B in their shopping cart? I've tried searching the forums about this and I can't really find anything. Thank you for any help.

[Ajeh]

You'd have to customize this ...

What would stop me from ordering Product A on Tuesday and Product B and Product C on Wednesday?

Can you better explain why you want to prevent the products from being purchased together?