If you live in a community where the police can be used to
assist families (and that is a BIG "if"), perhaps you could
tell your son unequivically "I have contacted the police deptartment and requested that they monitor our property to
make sure no unauthorized visitors show up." Frankly, I lied about that but the word spread and we did not have kids showing up. I also installed motion detector flood lamps outside that made it apparent when anyone went in or
out.
Did it solve the problem?? No. But it did reduce the
traffic.
We are all here to support you. Most of us have been there done that. It is ugly and not at all what any of us expected. Sending hugs your way. DDD