i was actually going to suggest brother, so that works perfectly! mercedes is 38, so he probably wouldn't be that much younger than tony. and i kind of had the idea that she never quite got the biker thing, either, but she loved him and so she loved the club as well - against her better judgment, lol. that's probably why it didn't take her much convincing when asked to be their doctor. i think that she would have talked to his family a bunch about who was going to raise his daughter, and maybe it was agreed that mercedes having her full time would be better because she would have a stable mother figure? and i think she was around from when the little girl was really young, too, maybe a year or so. she would have kept close with his family a lot.