soon to be husband adopting my 2 yr old daughter.

We are getting married in December of this year. And we have been together almost 2 yrs. We have a 9 month son together. And hr had taken my daughter in as his own since we started dating when she was 3 months old. She knows and calls him dad and is very attached to him. He wants to adopt her when we get married. Her bio father is unknown. Will we have any problems getting this done since he is unknown?