I Have a Question

Nothing you can do but be there for her. And make sure you stay out of trouble for her

All you can do is try and be supportive.
To both your mum and your brother.
Try and understand that we ALL have to make decisions as to what we do with our lives.
And, sometimes we fail!
But sometimes we don't!
Maybe your brothers spell in jail will have taught him that jail isn't where he wants to be! And he'll do anything to avoid going back there!
But in either case. The decisions he makes will be his own. And he is the only one who has to account for his actions!
Try not to worry too much.
It's in a parents DNA to worry about their children!

Tell him you love him and don't want him in trouble because without him around as your brother you get upset

I've been there. We were lucky enough that my brother turned his life around and never went back.
Are they sending him straight home or is he going to a halfway house?
Those going through halfway houses first are less likely to return to jail. Idk if that's an option for your brother or not.

I guess you and your mum could just be there for him and let him know that you love him and really don't want him to go to jail all the time, hopefully turn his life around. he biggest thing is protect yourself from any involvement with his activities. Good luck to you and your family.

All you can do is offer your support. Your mom will have to face reality