I was wondering my daghter is three years old now and my fiancé has been raising her since she was born. On her birth certificate there is unknown father as well. Can I put my fiancé down as her father? The biological father does not want anything to do with her. He has been in and out of jail her whole life. He gives no attempt to see her at all. What can I do to get my fiancés name on there?

No. A birth certificate is a legal document. Your fiancé is not the father so saying he is would be perjury.

Your fiancé can adopt the child using a step parent adoption. However this requires he be a step parent.

Contact a local Family Law attorney who can tell you the requirements and process for him to adopt.