I have read a few threads where people RSVPed and added additional guests that were not included on the invitation. Silly me I thought "that would never happen to me" since our RSVP website has all of the names entered in already and so you can only RSVP for people on the list. Well, somehow FI's cousin was able to get around the system and added a name to her RSVP. We had no idea who this person was so FI called his mom for info. Turns out this cousin does not want to sit in the car with her parents for an hour and a half by herself so she invited her BFF. The worst part is FMIL knew about it and never called FI to ask if it was ok. Thankfully we convinced FMIL that this is not ok, but FI is not happy about having to call his cousin to let her know that her BFF is not invited (he is kinda shy and does not like confrontation). Luckily we are only waiting on 10 more RSVPs so I don't think there will be any more issues, but come on people! If your name is not on the invite (or your invite does not include a plus one you) you cannot come.