The FI and I are on a really tight budget. He comes from a large family, and to keep the guest list manageable we instituted a couple ground rules for who got invited and who didn't. These rules were applied to everyone on the list, and with those, we kept our list to a size appropriate for our venue. All the invitations were addressed per the standards set by general etiquette, and there was no way to misunderstand exactly who was invited.
One of uncles called FMIL and asked about bringing his (not living at home) children to the wedding. FMIL explained that due to budget constraints and a lack of space at the venue, no, he could not bring them along.
Low and behold, we got an RSVP for not 2, but 7 people - his aunt and uncle, three cousins, and two second cousins.
It has already been explained to this uncle that we cannot afford for all these people to come, so I'm not sure another phone call would help. I'm kind of at a loss for what to do at this point. Any ideas?