Wascally,
I've set my boundaries and will not let my son live with me, but when I think he is in danger I have him taken to a hospital. I've learned to tell the difference from manipulation and real danger most of the time. Either way he can't live with me when in active addiction. I've had him taken to the hospital 3 times and each time had positive results. It did not cure his addiction, but it got him past the suicidal depression.
He will either have to threaten suicide or threaten others to have him taken in. Just being homeless is not enough. He can also admit himself.
There have been other times when my son was just without a place to go because of the choices he made and this is a different situation. Being homeless was a consequence of his own choices. There were times he had to steal food. There were a few times he was arrested. These were all his own consequences. There really is a difference between mental health issues and bad choices and manipulation. It's tough to make decisions in the middle of it. If I am in real doubt not knowing which way to go I have him taken to the hospital if I can. If he threatens to harm himself you can call 911.
You can also have numbers of shelters on hand to give to him. He can stay the night in a hospital emergency waiting room. They usually don't know who is waiting to be seen. He can check himself into a mental hospital if he wants help. They can help him locate treatment. He has lots of options. If he won't choose any of the options there isn't much you can do if you can't get them to take him in.
There are risks to their addiction and sometimes we can't change that. I've tried just about everything. Rehabs, hospitals, psychologists, psychiatrists, jail, picking him up off the streets, having him live with me, kicking him out homeless, you name it. They will find the way when they are ready. The more I can give him responsibility for his own life and recovery the better chance he has. Any time I can let him pay natural consequences for his choices he has a better chance of changing his choices.
Most of it is out of my control and it's very, very hard sometimes.
Hugs,
MG