You are a good man, Chancedon. Love is what love does, and you sound full to the brim with it. I've heard it said when it comes to organizations, including families, that "The Fish Stinks From the Head Down". You are keeping your family intact with your love. That is your only responsibility. Offering them a safe place in your heart to figure out their life. Between love and prayer, love is your best bet, but prayer helps clarify what you need to do. Continue to do so and leave the rest to whatever power has been punted to the future.
My daughter was chastised once by her boss (fast food counter) because she was caught on camera passing an amount of marijuana to someone over the counter. She came home upset and told me about it. We worked through it. When I later had a casual conversation with her boss about it, I thanked him for his tempered reaction to the event. He was shocked that I even knew. He said, "Your daughter told you that?". I told him if you don't shame the ones you love about their life (because yes, life is difficult as hell), they will feel safe and loved, and they will come to you, and you may not have to give them up to the world because they could not come to you. Stay away from shame. It tears and severs. Your son in law needs to learn that.
Interesting..... I'm a drummer too. Kudos to your son.