Linking AD group to custom target system account

I have set up a custom target system so that the account definition is tied to several business roles, so that certain Persons are automatically assigned an account based on this.

My question is, how do I tie an AD group to this account definition/account so that people with this account are also added to it.

I suppose I could add scripting around my custom target system through UNSAccountB_Insert/Delete so that they're added/removed along with the account, but I was wondering if there's a more native way of doing this.