Boundaries with Family

My husbands cousin recently had a baby and my MIL said something that makes me nervous for when we have children. Husbands cousin talked about what he does to help with teething and MIL comments, "yes you can do that", "that's ok" as if he was asking. He wasnt and it was clear that their constant comments and question about new babies development made new mom uncomfortable. I also know MIL has bad mouth the mom at one point and now wants to be all over their baby.

MIL tells me things we need to do in our house like where to place things or what to add or minus. We have handled that with gently reminding her this isnt her home.

It isnt quite the same tho as our child will also be her blood too and I dont know if that would be hurtful to use that same response.

Any suggestions on how to set healthy boundaries with in laws?

I just dont want anyone making my first time experience awful, does that make me awful?