When I was a tween my parents took in a teenage relative who was in a gang, into drugs, solicited himself for money, and was in big trouble with the law. That was the first of many troubled violent youths that they and we have taken in over the years. I am grown now and while I myself dont want to get into that sort of thing, I would if it were this sort of situation.
I can say from experience that boys in that situation, living that sort of life, being in trouble and causing trouble- theyre scared shistless. ABSOLUTELY Shistless. Thats why they function on the remedial social level that they do. theyre depraved. They have no hope, no options, and no matter how much they WANT to please and do right, no matter how well they can see the right choice to make, they lack the training to know HOW to DO right, in any kind of consistent worthwhile manner.
Being a man in this world is hard, you spend your life trying to be big enough, strong enough, smart enough, quick enough, savvy enough so that no other man has a chance to notice and call you out on some weakness. Boys like these are thrust into that existence at too young an age, they have to be men, in the animal survival sense, without the ability. They survive on BSing and puffing themselves up. It stunts the development of the other social skills needed to be functional.
Anyway, what you're going to find yourselves doing is part therapy, part guidance, and part rehabilitation. And that is in itself hard work. Not just for you, but for them. You have the foresight to see a way out of their situation for them, but they are just as equally unable to believe or see such a hope. And on top of it all what little security they had in their own family has been abruptly taken away completely.
You'll make it though. Just have the solidity within yourselves and your family structure, and the grace to see even the smallest efforts and change. You're dealing with three grown men who have the emotional and social skills of young children.
Pull through for them, they need it!