Your family is in a tough spot. It's important that you family has some strong rules and conditions for your brother to stay in your house.Your brother should also be participating in a program. As far as the girlfriend, if she is using and he is hanging out with her chances are that he will continue to use. As much as I would hate to see a child in foster care ( I raised my brothers 2 kids for a few years) that child would be better off. If the child is placed in care, CPS would assist your brother and the mother of the child in getting help.The courts will drug test them.Their visitation will be supervised. They would have to follow a plan, otherwise they will lose their parental rights after so many months (over 2 years I believe). If the child is with the mother and the child is removed, CPS will possibly place the child with your brother. If your brother is clean and he doesn't have any court case against him, he may get custody. It's important to speak up, especially when a child is involved. Your brother can make any kind of choices for himself that he wants but when it comes to the safety and welfare of a child, you have to speak up.Your brother decided to have this child and it's his responsibility to take care of it (Financially, emotionally and physically. If your family chooses to help out with the child, then that's their choice and NOT your brothers. The bottom line is that your brother has to help himself. He needs a program, he needs to get a job ( Is he working?) . Your parents may want to think about how long they want to let your brother stay. If your brother knows that he doesnt have to really help himself then what would motivate him? Good luck

You and your parents have learned how not to enable now you have to step back and let your brother handle his addiction. It up to him, can't make him do a program and besides most people quit on their own by their own means. There are lots of different ways he has to find his way. I helped a friend get her husband to sober up, all I did was give her some books to read and she left them laying around the house while she was reading them. He was still under age 30 and his addiction hadn't gotten so back he couldn't see, hey if I don't straighten up she's leaving. So try leaving some information laying around. If he is really earnest he will pick some of it up and start reading.
It sounds more like he is on a fishing expedition and trying to see how much you all really mean what you've said. So don't buy into it. So instead tell him its his life, and let him be responsible for things that are his responsibilty.
Also if he's living with your parents he need to help out around the house.

Thank you both. Boundaries have been set and my parents are trying their best to be serious about them, not succumbing to accusations, manipulations and threats.

When he gest angry and verbally abusive, without having been provoked, should they confront him or just let him scream and shout?

He's doing things that are weird... I'm embarrased to say what...

When ex would scream and yell it was because I wasn't letting him manipulate me. So he would try the bully method, that didn't work either. I think your brother is doing this because he isn't able to get his way. No one is playing into his manipulations so he lashes out, he knows in the past this worked so it has to work now. Except don't play into his manipulations, if he is calling hang up. If he lives with parents they need to let him know it is a privilege to be a grown adult and live in "their" home. He can no longer yell and scream if he chooses to yell, scream he will have to find himself another place to stay.
Do not ingauge in his game, if you do he has won. Instead walk away and discuss his actions when he is sober or has calmed down. But make sure he knows the family will not be held hostage by him.
Think of this a child throwing a tantrum to get their own way.

You're so right. He does act like a child. My mom is holding strong though. Thanks Katrinka, thanks Truedy..