I was thinking the same thing - if their relationship is not that great why would OP let her be responsible for something like this? The only reason would be that she is paying for most of it if not all. In that case OP deserves it and should have not agreed to having him and his fiancee treated this way.

They don't always suck! My aunt and my cousins' wife get along fine when they visit (2 hr drive).

Well when you unscramble mother-in-law you know what you get.

14. Yes, correct form.

Good idea but they're usually very expensive. Most people get really nice quality cards. It might be a pain in the ass to order more

When first reading this, the idea popped into my head that they should change their venue and send out new cards, but not send the new one to the mother in law. Then I realize how tremendous a pile of work that'd be, and that'd be much easier to just tell her they're changing venue. Best case scenario she falls for it and doesn't show up, middle case she's late, and looks like an ass, because she went to the wrong place, and worst case she catches on and makes the wedding worse than before. It's a gamble, but roughly 66% chance of effect.

#39 I like your thinking. But the math is incorrect because there isn't a way to ensure that all three scenarios probability are weighted the same.

if she's a robust woman tell her "we saved these three seats for you"