What would you do

If your brother in law comes to your house every day with his wife and 3 kids and he's sitting in your living room using your internet to watch football (he doesn't have internet at home) and in the meantime his kids are wreaking your living room right next to him?

I get it they are kids but if I'm in the room nobody draws on anything.

So I went to my living room today and saw numbers written on my table and one the walls. It was his little autistic son. He also teared a peace of paper and spread it all over the room and put food on the couch and left it there. So I was snapping at his father today. Why can't he watch his son if he knows he's going to do something stupid?

It's not the first time. Just a week ago he was alone in the bathroom and used a glass to to get out water from the toilet and pour it on the carpet in the hallway.

Two weeks before that he pooped in my sister in laws bedroom and used his poop to write numbers on the wall.

I get that he's autistic and it's not his fault. I would never blame him. But it is his father's fault! All he does is beat his son up and go home. He leaves the mess for us to clean.

So I told my husband today that I don't want to see them here again or I'll move out the very next day. I know they'll still come anyway. But what else could I do to make them look after their child without wrecking my house??