Anonymous wrote:Sibling of the BIL needs to have a conversation with him.
Yep.
You don't want the kids to grow up thinking it's OK to sit around in your undies.
I had a friend's child stay with me for a few months when the kid got a big city job. This person not only walked around in undies and shirtless, but belched, burped and hacked out loud unapologetically. My guess is this was normalized in the house where they grew up.
I could NOT wait for my hosting duties to end and turned this person down when they asked for another month or more of lodging.
So if you don't want your child behaving this way, or accepting it of others, don't normalize it.