My dad was an alcoholic. I became an alcoholic. The first thing you need to do is make sure he understands that he CANNOT stop his mother from drinking or using drugs if she isn't ready to quit. Alateen or al-anon can help with this. He (and you) also need to understand that alcoholism runs in families and children of alcoholics, whether they feel like they're in danger or not, need to be careful around alcohol. I mean no offense by this, I never in a million years would have thought I'd inherit the problem. i wish you both the best of luck.