i knew a couple who adopted a little girl, she was 5. sweetest thing you could ever imagine. when she was 13, her birth mother (who had various addiction issues, DV and a horde of other problems) got in contact with her. You cannot stop a birth parent contacting their child, even once they've given the child up. Little girl went from being an ordinary teenager to being out all hours, smoking, substance abuse, a string of older 'boyfriends' found for her by her birth-mother's partner. she stole from her family home, was brought home by the police all the time.
When she turned 17 her parents had no choice left after years of abuse from her than to change the locks. she broke in and smashed the place. Eventually they had to move.
They still loved her, she was their little girl, but they had to abandon her again. that makes me sad.