I have a good relationship with my MIL. I wouldn't say it was great because we are quite different people personality wise, but we get along fine and have never had any sort of issues. I will add that she is the type of person who is always right, no matter what and I learned early on how to navigate this.
Me and DH are TTC (not having the best luck due to some MC) and she made a comment today that's sent my head spinning trying to think of how to fix the problem before it arises.
We were discussing someone in the family who has recently had a baby and that she's struggling with too many visitors. I was on the side of the new mum and MIL wasn't. She then said "well when you have a baby I'll be here every day and you wouldn't be able to stop me". Knowing her personality and not wanting to have an argument about a baby I haven't conceived yet, I just moved past the comment.
This was not a joke, just to be clear.
Now I'm left thinking the only option is to barricade the doors or emigrate. She lives 10 mins away.