Citizenship? US Step-father, LPR Bio-Mother

Hi,My wife is a LPR, and so is my step daughter. I need some direction on how to adopt my step-daughter (4 Years Old) I want her to have my last name. My wife's last name was changed when she because LPR, but I couldn't do the same for my step-daughter. Could you please help me?I live in TexasThanks,Aliinstacell2@gmail.com