what to do

So my older brother and his girlfriend had a baby together last year and since she's been really like crazy, to the point where they went to court because she beat her other children, so it was a custody battle, but like last month they got back together and decided to like share the baby. But she went homeless so she moved in with us bc her mom and step dad couldn't handle her anymore and so she's been living with us under a couple conditions: her other two kids had to go to foster care and she had to get a job and help pay rent, but she hasn't been paying rent and idk what would you do with her? She made really bad lies about my brother in court so some say we should of never let her stay with us in the first place. Her 5 year old daughter isn't in a foster care so well my mom doesn't want to throw her out to go live back in her car again, it's not my choice on what they chose but I just want to know what you all think. I mean my brother and her did have a baby together so I guess it's family and in my family we always do whatever for family, but is what she did worth it? She almost took away my baby nephew from us yet she was the one who was crazy.