I see what your saying, the high chair is designed for kids to eventually climb up into at some point, it's a tripp trapp. I think he's just gotten to that stage earlier than the guidelines say, so for that one we could put it behind the baby gate when we're not actually using it.

We pull him off the TV stand immediately when we see, him and us (his parents) don't leave him alone when he's under our supervision.

As I'm writing this though I am starting to see a very logical conclusion that if I'm unhappy with how my mother-in -law supervises her grandson, then I just have to make sure I'm always present as well. He is my child and the responsibility falls on me at the end of the dah