For whatever it's worth, I know a bit about Timeshare Relief. I'm not familiar with the swap described in the initial post however. Perhaps this is in relation to a company other than Timeshare Relief. At any rate, I posted a while back in response to another timeshare related thread with my thoughts. You can read it here:
Timeshare Relief
My understanding is that they charge a fee to take your timeshare off your hands and that it is a complete transfer of title. Once you complete the transaction it's a done deal. I also know how the timeshare industry works (used to sell them) and can vouch for their dislike of ANY company that dares to expose their shady business tactics as Timeshare Relief does. Keep that in mind when doing your research. A lot of what you see out there is put out there by timeshare sellers and people with a vested interest in keeping the timeshare "dream" alive.
Good luck.