TOPIC: Jomsocial Group Discount

Hello,

We need to give a 20% discount to all of our members for each event registration.

We keep track of our members by keeping them all in a Jomsocial group called "Members".

Right now DT Register seems to give discounts to any users who is active and registered on site.

Is there a way to assign a Jomsocial Group to get discounts and not any registered user without hacking the code? And if we need to hack it, where should we look?

thx,
Jack