My sister is having baby in march of 2010. He ex fiancé is the father. She left him due to physical abuse a few weeks before finding out she was pregnant. Since then he has started a relationship with our cousin and broke up their marriage and has constantly harassing my sister. He has told her that he wants nothing to with her or the child. But he isn't all together. He has threated to take the baby too at times. She is extremely concerned out what he will do. He has falsely accused her of theft of her engagement ring and other household things from their house that she paid for. The police have proven his charges to be false. He has even been let go from the volnteer fire dept. she is wanting to make me and my fiancée responsible for the baby if anything were to happen to her but we don't know how to do that. Any help would be greatly appreciated.

As long as both the mother and father sign to give you legal guardianship, and it goes though the court and the judge signs it,

But she can not give you the child unless she and he gives up their rights to the child,

If the bio father does nothing, he will have rights to custody of the child if something happens to the mother.