Combining attribute quantities for discounts by quantity?

[ekdesigns]

I can't figure out how to get Prestashop to combine quantities with different attributes for the quantity discount.

 

Example, discount breaks at 12, 48, 144, 288. Multiple color options...so customer chooses 100 in red and 100 in green.

 

I want them to get the 144 price break for both as the total quantity is over 144...but instead it charges them the 48 count price for red and then 48 count price for green.

 

How can I accomplish what I need?