To not hold the black sheep accountable for their conduct enables them to continue the off conduct and hurt others. As long as they are not held accountable they will keep on doing what they have been doing, to their own detriment and the detriment of others.
Make them accountable for what they do. As long as they choose to continue the behaviour do not not help them do not rescue them. Do not provide bail, food, shelter, clothing, transportation, companionship, sympathy or understanding. Nothing nadda. That may seem harsh but the fact is that when you aid them you feed their disease help them die or hurt another.
Remember the path to hell is paved with good intentions.
Doing harm to any member of my immediate family can be fatal I do not care who is doing it. Luckily no member of my immediate family could ever even imagine hurting another member no matter what