Product Group and Inventory

Ok, let me lay out this concept simply…

We sell product A, B, C and D.

If a customer buys 1 pc of A the inventory deducts in CS Cart, works great.

I want to sell product E which is just A+B at a different price.

Right now I have a separate product for E and if I split my actual A & B inventory between A/B and E. While this keeps me from overselling my inventory, it means I may have A in stock but it is actually hidden in the E “kit”.

Is there a better way to do my E products in CS Cart? I don't even mind if it shows both A&B (plus a discount) on the cart once it is added by the user.