Adopted Child wants to come home

Originally Posted By Stacy K.The child I gave up for adoption wants to come back home to live with me and her biological father. She was adopted by her cousion. My child has been a part of our lives thru this adoption. I'v had three other kids since she has been adopted. They all get along fine and love each other so well. Where my child lives now she has no other sisters or brothers. She is alone. My daughter and I get along so well, you would think she was never given up. Now, she wants me to fight to get her home, and I want her back as well as the rest of the family. She is 13yrs old. Her adopted mother won't let me see her or my kids, because she told her she want to live with me. My child and I sneak and talk to each other and she is so unhappy. What can I do to help her?