Eek! Fianc�'s family is inviting extra guests!?

Yeah, I'd be mad, to say the least. I think you really have no choice but to pay for the extra guests. It's kind of weird to uninvite someone. As for the extra people that were invited to the shower, sounds like you're just going to have to have a bigger wedding. It's very rude of them to invite people, even after you've specifically said no, then refuse to pay for them. I guess you'll just have to wait until after the wedding to talk to them about it more. Good luck.