5, there *is* probably a way to do this legally that would let your brother access the inheritance without it being immediately seized to pay his debt. However, instead, he should stop being a fuckin' deadbeat and take care of his damn kids.

Smile and nod to them, wait and see - it could end up being a moot point, your mom's alive and healthy, she could outlive your brother, or she could end up having to spend it all on end-of-life care. But if things to shake out like you're all predicting, take your half and put the other half in a trust for his kids. It's win-win, they get their inheritance and he still has to pay his goddamn child support himself.