Maybe I'm confused or not communicating what I need. How do I apply a discount for each one when they're dependent on each other. If someone orders two of product with id "6" I need it to be the same as if they buy one of "6" and one of "7", or "7 & 8", or "6 & 8". So basically if they buy two or more of any of the products "6,7,8" I would like it to be $15 a piece... I need to have the cart recognize not their product ID but their group.