AS, do you recall how quickly they call for the phone interview after registering?
It's been many years but from what I remember it was very soon, like the day after we registered. In my case it was actually my XW that wanted to give it a try, in retrospect I think it was too soon and that she just wanted to do it to say she "tried everything". I looked at their website and all I can see about the interview is the following:
"First, you will need to Register for a weekend program. Once you complete the registration process, you will be contacted by the Registration Couple from the community where you will be attending the weekend. They will give you a short briefing about the expectations, and answer any questions you may have about the program."
So maybe they don't require that you promise not to be involved with an OP anymore. There's a 1-800 number you can call if you have any questions about that.