Limiting chain usage?

Hello,

Let’s say I have a ticket buyer named Adam. After he have bought a ticket, he get a nice little bonus; a coupon code (ADAM-XXXX) to give away to a friend. And the friend chosen is named Billy.

Now… when Billy using that coupon code (ADAM-XXXX)… will he in turn also get a coupon code (BILLY-XXXX)? Because that is not necessarily desireable. It would be nice to have this limited to people who have bought a ticket for the full standard amount, and excluding those who are using a coupon themselves.