This is going to sound stupid and whiny, but I need to write it out to people who aren't involved and can't get offended about the situation.
My FI and I have had a long engagement (2+ years) while we were saving up money for our wedding, as we knew we would have to pay for it ourselves. FIML decided to host our engagement party a few months after our engagement, but before we had picked out a venue. Despite the timing, we said that we were going to look at smaller venues, probably no more than 90-100 people invited to the wedding. Obviously, FIML invites 200 people to the engagement party she's hosting. Only 100 people came to the party, so she said it was no big deal (and I'm sitting there, thinking about how everyone who comes to the engagement party has to be invited to the wedding and how much I have already lost control of my own wedding).
We pick our venue, and it can do max like 110 people, because we wanted, saved, and budgeted for a small wedding and none of our parents can pay to upgrade to a larger venue.
I send FIML the list for the Save the Dates so she can proof read her friends' names for typos and get me the last addresses I needed. And of course I had to cut people out that she invited to the engagement party (people my FI and I have frankly never met or heard of before). And she's all "Oh so-and-so isn't on here. They were invited to the engagement party! You have to invite them!" I remind her of the size constraints of our venue and I already have 120 people on the list. "Oh they'll never come. You just have to invite them!"
So now my list is 130 people. Just for the Save the Dates. And you can't say no to this woman. Though, in hindsight, I really ought to have.
Now we get to mailing out the actual invites. FIML and FIFL have friends that will be slighted if we don't invited them. So we have to. Even though they won't come. Now we're at 140. Now FIML has friends she has known forever and are practically family and she can't imagine not inviting them. Even though they won't come. 155 people. I tell her absolutely no more. I have to cut a few friends out and cut down the +1's I'm allowing to make room (basically to longstanding relationships, the WP, engaged couples or married people. Single people need to be single. Please, dear God, they have to be single). I send out the invites.
FIML comes back to me, telling me she was talking to some friends and says they never got their invites. I told her they were not invited. She says they just have to be there. I remind her there is no room. They are not invited. She's all, "Why can't they come." And "Why doesn't anyone have any +1's. It's not right. It's not good etiquette."
FMIL finds out that some of her friends can't come. She starts inviting other people and saying to me "Oh, I heard so-and-so can't come. So I invited such-and-such. That's okay, right?" I tell her, such-and such can come, but no more. I do not have room as it is. I need as many Regrets as I can get. Anyone else she verbally invites will not be allowed to come.
FMIL loses it. Telling me she only has (lists like 20 personal friends, in addition to her huge family) coming. No one's going to be there. She can't not have these friends there. Why am I being like this?
Meanwhile, I'm getting RSVP's back, and guess who's coming? If you guessed all the people we just had to invite that would never come, you were right. There's a lot of out of state friends and family I have that I doubt can make it. So I'm sure it will work out...
But let this be a lesson and letting other people control your guest list. Just say no and handle the meltdown then and there. Because right now I'm alternating between hating myself for letting things get so out of hand and wanting to drink a bottle of wine, cry in a corner and pretend I'm not getting married.
If this gets posted to a place FIML can read, this will also be a lesson in venting to others. Please don't get me wrong, she's a sweetheart. and really lovely..so long as you're not attempting to plan a party and maintain any kind of control or voicing a complaint.