Hi all, I need some etiquette advice on inviting different circles of children. When FI and I got engaged last spring we did an initial guest list so we could come up with a rough number of how large the wedding would be (we want to keep it relatively small). We decided on what I consider immediate family; parents, siblings, aunts, uncles, cousins - and then we each invited a few close friends. We decided to allow kids at the wedding since it would end up being just our cousins plus 1 non family child and we could still fit within the number of people we wanted.
Last night during dinner I tell FI I want to go over the list again and finalize it so I start listing off everybody and when we get to two of his friends and their wives, he says "wait, we don't have to invite their kids right?". He never mentioned before that these two couples had kids - apparently one couple has 2 and once couple has 4. He says he's only met the children once at a wedding. So my initial thought was "no" we don't have to invite them. And then my second thought was that they would be upset if they got to the wedding and saw a bunch of other kids but we didn't invite theirs. I guess we could invite just the circle of kids that are family, but that means the 1 non family child (we'll call her Sarah) that was going to be invited now shouldn't be right? I hate to not be able to invite Sarah whom I know well because I don't want to insult FI's two friends whose kids we basically don't know at all, by not inviting them. What's the correct way to handle this?