Hannah asked in a comment for advice when welcoming a 16 year old boy into her home -- a foster son.
I'm going to start a list of ideas, and then maybe the rest of you can add some..
1) PIck your battles.
2) Don't sweat the small stuff.
3) Self differentiate.
4) Do not get sucked in.
5) De-escalate by not getting yourself riled up
6) Read Yondalia. She's the queen of teenage boy foster care,,,,