My daughters father has not paid child support in over 5 years I do not know where he lives or works, however my fiancé wants to adopt her since he has raised her all that time, how can we do this after we get married if I can not find her birth father?

You will need to check the laws where you live... in most states they want you to be married at least a year before allowing adoption. But every case has circumstances which may make it different.

Once you find out all the laws and what you need to do... you will need to retain an attorney, it will just make things easier. You will have to make a good faith effort to locate the biological father. Most of the time this is done through an ad in local newspapers announcing you intent to have the child adoption. The bio father is then given "x" amount of time to respond and either willingly sign away his rights, or fight it. If the bio father does not respond in the given amount of time, you can go ahead with the adoption. :)

Good luck.

You have to get his approval or make a good faith effort to do so. Since you will need an attorney to prepare the adoption papers, that attorney will advise you on what you need to do to terminate his rights. And yes, you should wait until you are married first.

Oh my goodness! I went through the same thing. First, I live in Pennsylvania. My ex is one to move around a lot and he can only hold a job for so long before he decides that it's not for him and moves on to something else. So trying to find him, is like looking directly at the sun when it's at it's brightest and seeing things clearly right afterwards, you know what I mean?
My husband has been raising my son since he was 11 months old, ao he is his father even if not his biological one. So, my mother in law decided it was time to get my son adopted so he could go to school with our last name and not have my ex's last name. We went to an adoption attorney and we told her our situation and she set about trying to find my ex. She looked at all of the court papers and employment records and couldn't find him. What happened next was she placed an ad in the newpapers, and had a different kind of adoption in mind, It's called an abandonment adoption. The attorney said that in the first place, he hasn't had any contact in several years and after 6 months of no contact, that is considered abandonment.
So, in my story, everything worked out. No one responded to the newspaper ads, and the adoption went off without a hitch. Good luck to you and I hope you have as good as an outcome as we did.

In Missouri you can do it without the absent parent's signature based on grounds of abandonment as well. The length of time the other parent has to go without seeing the child depends on child's age and if they are paying child support. Here, they have to go so long without contact with child and be 6 months behind on child support. One of my friends is going through this now. The dad doesn't want to be in the child's life unless he is with the mom in a relationship, she has moved on, he doesn't see the child, but he pays child support because it comes out of his wages. He won't sign over rights, so her husband can't adopt. And, he adopted her other child before they got married. They had been together for 5 years, was the only father known to the child and the child's father signed over rights if she agreed to drop back child support due to her.