My sister in law wants to let us adopt her unborn child. I know she can relinquish her parental rights. I need to know what paperwork I have to file for the father to relinquish his parental rights in ca. And can anything be in place before the child is born so we can bring the baby home with us from the hospital with out running the risk of the child going into the state's custody?

How far along is your sister in law? Also do you think this is a good idea or is it going to cause problems later?

You should talk to a lawyer to be sure but you can set most things up before hand. The problem is that in order for the father to relinquish parental rights he would have to be proven the father first in a court of law. Then relinquish his rights. You need a good lawyer for all this. Is the father willing to go along with it or does he even know?

It can not take place till the baby is born, but most of the paper work can be in place for when it does.

She is only about two or three months pregnant. She told the father, he was told and he said "how do you know it's mine?" He has made no attempt to contact her or find out more information about the pregnancy this was about two months ago. . She only knows his first name and where he lives apparently this was a one time thing. I don't see any future problems we have spoken very openly about the matter and she has made very clear that she only wants to be auntie A lawyer we spoke with said we couldn't do anything before the child was born as far as adoption goes. He said we would have to do guardianship first is that true?

At this point the bio mother will have to file in court to prove paternity of the father with DNA and then see if he will sign over his rights. ( of course knowing he will not have to pay support will help)

So without bio father working with it, there will be a lot more time and a lot more money involved to make it happen

Yes, the adoption process is not immediate. So you would file for guardianship to take effect upon birth. This will allow you to take the baby home.

From there you file for adoption, which will involve establishing paternity and getting the father to relinquish. It would be best to use an attorney to make sure all the paperwork is done correctly.

At this point the bio mother will have to file in court to prove paternity of the father with DNA and then see if he will sign over his rights. ( of course knowing he will not have to pay support will help)

So without bio father working with it, there will be alot more time and a lot more money involved to make it happen

Agreed!
But there is an easiest way-he may sign Acknowledgment of Paternity and relinquishment of parental rights.
CalCourtForms - Marin County Superior Court Forms - Termination of Parental Rights (http://calcourtforms.com/forms/ca/marin.msc/par)

California Courts: Forms (http://www.courtinfo.ca.gov/cgi-bin/forms.cgi)