you could always ask him
"son, what would you like me to help you with in your struggles today?" and I mean that in a caring way - not in sarcasm.
Maybe ask him are the specific areas you would like for me to pray about for you?
Would you like some company at a meeting?
Can I share a reading that meant a lot to me today?
For me, this is about letting them still be in control of their recovery - I am being supportive, but not controlling. (which is easy for me to slide into as a parent)
Keeping you and your son in my thoughts & prayers,
Wishing you Serenity & Joy,
Rita