My daughter is now 3 years old, neither of us have had any sort of relationship with her biological father since my daughter was 3 months old. I have been in a relationship with my current partner for 2 years and we are due to have another baby next month. My current partner has raised my first child and provided for her financially (we receive nothing from her biological father) we would like for my current partner to have parental rights to my daughter, how do we go about this?

First, you will probably need to be married for a time. Most states require a couple to be married before approving an adoption.

You should start shopping around for a Family Law attorney. The attorney will tell you what you need to do and prepare all the paperwork.

You would have to marry and then after about a years time have them adopt. You will need the bio fathers permission for the adoption. Is there a child support order in place ?

Most, but not all US states will need to see the word "married" and normally for about one year.

The bio father will have to sign over his rights to allow the adoption.