What is 'adopt as care dependent'?

My sim got this option with a neighbor kid that has two parents and lives next door. Their relationship is high. The child would come over after school to play with my sim's daughter and have after school snacks at her house and she got this option. I've never clicked it so I have no idea what it would have done had I clicked it. I'm curious if it moves the child into her home or whatever it might do.