L.C.
I understand that you love your sister. You want her to do the right thing and you want good things for her. The hardest part, especially when we love someone and are so invested in them, is accepting the fact that we can talk, warn, beg, plead and cry but only they can choose. Her life is not going the way she planned and she is still reeling from that. No, she never wanted to or planned to be a single parent. She is overwhelmed and doesn't want to be alone. So even if this guy she is seeing is a bad dude, she might be more than willing to ignore the warning signs because it seems so much better than being alone with the overwhelming responsibility of a child.
Which brings us to the real issue here. This little baby is at the mercy of her moms choices. As much as you don't want to do this, CPS may need to be brought in the next time mom disappears. She can't be passed around and she can't be brought into a situation with a potentially violent person. She may only get the big picture when her family stops enabling her and allows her to face the consequences of her behavior. And it is probably the very best thing for that baby. If CPS gets involved and is the baby is removed, the family has the option of taking the baby before she is put in fostercare. The state would also provide financial assistance, medical coverage, daycare if necessary and any intervention that helped keep the baby with the family.
Just some thoughts,
L.