Sorry Mom, I may have misunderstood the question.
In the DS160, in the F2 visa, her surname is indicated as it is on the birth certificate.
I had a question as to what if I indicate myself as a father to my stepdaughter in I485, because I consider myself as such, after all, I married her mother. But at the same time, I did not make an official adoption, and in her birth certificate, her biological father is indicated as a father.
Wouldn't it be a mistake that I identify myself as her father, while I am not hiding any information, because I am providing a birth certificate that says otherwise?