Fix opencart function

I'm working on an OpenCart 1.5 store, and they want to have a minimum order amount for the various t-shirt designs that they have. First off, the overall order must be at least 12 items of any assortment. Most of the apparel has size breakdowns (XS through 4XL). Each of the apparel styles can be screen printed with one of seven designs. They want each design to have a minimum of 6 when ordering – this can be spread out over any screen printable item. For example, a customer could purchase 6 shirts with design A, and 6 hoodies with design B to make up the minimum quantity of 12. They could also purchase 3 men’s t-shirts, 2 women’s t-shirts, and a tank top with design A and a similar quantity of design B to make the minimum of 12. If a customer tries to order less than six of any design there should be an error asking them to add more products of the design. The minimum cart total of 12 items works fine, the issue is if a customer doesn't order the minimum number per design, the system won't catch it. I came up with this validation in catalog/controller/checkout/[login to view URL] around line 196 I'm looking for someone to make this function work properly (please see attached file).