I was just a lurker in the forums when I scheduled my lapband surgery, but I knew I would have family that would make my life MISERABLE by trying to talk me out of going to Tijuana. To stop that before it started, I paid my deposit, bought my plane tickets, and had websites ready to email each member of my family. When I told them, and they started their tirade, I just told them that it was too late, that the whole thing was already paid for, and they could bitch and moan all they wanted to, but it wouldn't change anything. Amazingly, it worked, and none of them had anything to say about it after that.
After I returned from an amazing trip, each of them grilled me for details, and were amazed that I had such a wonderful experience at such a new, beautiful, clean clinic with amazing doctors and staff.
Anyway, that is the way I handled family.