Can his live in girlfriend or EX now take away his kids from him if there in a stable environment and she is leaving my brother for another man in another city and a sex offender at that? My brother has them in his care as we speak can she go to his house and walk out of there with them. They are not married but have to kids. One is 2 and the other is 1. What does he do he is so lost and not familiar with his rights? We all are not sure we need help asap. This is happening as I type.

Does he have legal custody of the kids though court? If so, she cannot just "take the kids," she would have to go back to court to get the custody changed. If the new guy really is a sex offender and is registered, I can't see a judge okaying the move.

He needs to go to family court and let them know that she left them in his custody and he wants full rights. I am not sure what he can do asap other than change the locks. He can notify the police too since the boyfriend is a sex offender.

Your brother needs to protect his kids from his ex and her new love Go back to court go before the judge and let the world know that we will not allow sex offenders to hurt our kids but the way it sounds your brother has his sis looking out for him. Your brother and has kids are in my prayers and good luck

They will need to go to court and get a order of custody

In my state psychical custody means everything unless she has court orders. She can not come into his home and take the kids. I don't think they would be outside alone for her to snatch them. You need to get temporary emergency legal custody before she does. Then the fight will begin, but until it is settled the kids will be with daddy.
I can't see any judge giving custody to a lady living with a child molester, but you never know, Get a lawyer, as in yesterday.
I am no lawyer, but my son has custody of his daughter and has had her for 10 years. His situation was a lot like yours. Good luck