If this is what you want, what your husband wants, and what your daughter wants, that's really all that matters.
You will need an adoption lawyer....I have a fabulous one if you want me to PM you the info. In Ft Worth, they have "adoption day" a few times a year where they set the courtroom up with balloons and stuffed animals and spend the day finalizing adoptions. The judge is fabulous, poses with the family for pics, etc. The atty's paralegals even will help with pics and videotaping the ceremony. Afterwards, they let your child choose a stuffed animal. While you wait for your paperwork in the jury room, they have refreshements set up. It's a very celebratory ceremony and occasion. In all, it took us about 2 hours to finalize the adoption (I adopted overseas, but TX requires readoption too.) The State will reissue her birth certificate with your husband's name on it, and it takes about 4 -6 months to get the birth certificate back correctly. (Expect it to be wrong the first time.) Even though you don't live in Ft. Worth, you can do the adoption there. (I'm not sure why that's the rule, but it is.) With is being a step father adopting her, I'm not sure whether the State will require a homestudy to approve the adoption, but I would suspect they will. Expect a homestudy to run about $1,500 - 2,000 and finalizing the adoption to run somewhere around $1,000. Not sure of any other expenses or steps.