I have a question on proper etiquette surrounding a specific rehearsal dinner circumstance. Originally, the people invited to our rehearsal dinner were those people attending the actual rehearsal. This included our parents, siblings, and wedding party (and, of course, any of their SOs). This is how I've seen most people do it, and it was agreed upon by all family members, so we thought we were all set. Since then, 3 people have RSVPd that they can't come to the rehearsal. This happens, and it's totally fine. My fiance's family, however, would like us to fill those 3 spots with 3 other people. Here's where we come in to a problem. I originally thought that we could include the grandparents, but there are more than 3 living grandparents. I wouldn't want to invite just 3 of them and not the others. I don't want to insult anyone by doing this. The same goes for aunts/uncles, cousins, etc. Three seats really isn't enough to open the dinner up to a whole other section of family. My fiance's parents are paying for the rehearsal, and there is a food and beverage minimum that they are being held to. They want to fill all of the seats that they made the reservation for so as to get the most out of the money that they are obligated to spend with the venue anyway. What should I do?