I’m going to challenge you for a second and kind of just ask you a question.
You say everyone treats his son like a king and he wants to control all situations and everything needs to go his way.
In your last sentence you finally gave in to let him have the satisfaction.
Isn’t that what everyone does for him? You just did it too.
I imagine it’s the easier way when you just don’t want to deal anymore.
Also, M had made it very clear to me that I would never be discipling his child. He made it clear in a passive aggressive way, but he made it clear. Perhaps very very gently would be ok, but otherwise, it was a nope. I was scared to say anything to the kid that might be along the lines of a “no” there a few times I also had to tell my daughter “just let him” when it really wasn’t fair. I felt bad, but my daughter is much older and she could handle it better. M also treated his son like he was the boss and gets to make all the choices. Probably why his kid was getting in trouble in preschool. He didn’t get what he wanted and acted out. He was used to getting what he wanted.
Anyways, I know the doctor is much more flexible in allowing you to stop unruly behavior and she probably wants some help. M’s son walked on water and he was the best parent alive according to himself. So I basically couldn’t say boo.
Do you feel afraid of not giving him his way because his mom might not like it? If you want to change the behavior then you might have to be the first one not to let him get his way. And might not want to tell your girls to let him have his way too. They are pretty much the same age and they are dealing with a very immature kid, but not one who is so much younger.
I’m just saying , if you see all of you living in the same house one day, his behavior won’t be as sustainable for you or your girls if he doesn’t get a little tough love. Easy now when you just hang out. But living together? Might want to nip that one in the bud.