Switching referral under someone else?

What I am wondering is

I signed up under this person, but then I wasn't able to green for them, due to some trouble with the offer I picked, and so I ended up paying him for his green because it was a trade. Since I haven't credited yet on this site, would I be able to get the referral switched so that I would be signed up under someone else? The person I'm currently under has already approved for his gift I believe, and I wanted to try out this site, but I only really want to do it if I can get paid for it/referral in return for it.

Trainn doesn't allow this.