Modify CMGroupbuying extention for Joomla

Need to modify the extension CMGroupbuying for Joomla 2.5.11 for a new website. Modifications include: Enable two separate coupons to be sent to the buyer for two different merchants from the same deal. Each coupon will have separate coupon codes and can be created and edited completely separately. Create two merchant groups, a primary group and a secondary group. Each merchant group would have all the function of the CMGroupbuying platform separately. The consumer would select a deal involving the primary merchant and then as an option select from a list of secondary merchants to create the deal. Create a tracking system for the coupons as some of the coupon price will be paid back to the secondary merchant group. A system exist in the CMGroupbuying software to track what coupons are paid buy the consumer but we need an addition tracking system to track what exchanged coupon have had a percent paid back to the secondary merchant. Also we need some frontend minor template changes and some Java script for some automatic calculations shown in the frontend. Will be using: Joomla 2.5.11 CMGroupbuying 2.4.0 Communitybuilder 1.9 Profile Pro for Communitybuilder 3.1