Re: DD really wants to know her father
I agree with Erin. Be honest. The longer this goes on the harder it wil be for her. She may feel like you lied to her. I would make it clear that that man is not her "dad" he is her "biological father". Explain that a biological father did help her grow in your tummy but that a "dad" takes care of you and loves you everyday. I would make it clear that she is a very special gift and that you are greatful to the "man" for giving her to you but that he isn't a daddy. kwim? Just my 2cents.
Just in case.