I don't know that she can attach to you since those she was attached to, her parents, have mistreated or abandoned her. My mother died when I was 3 and I know the women my father introduced me to, had care for me when he could not, did not feel like "mine" and thinking about my father not coming back to pick me up made me feel horrible when I was with them and not want to become attached (as it would make it "true" that he was not coming back -- magical thinking). Even today, at 64, I am uneasy being in other people's homes, my stepson's/daughter-in-law's and grandchildren's included, feeling they are "not mine" and I will somehow get stuck in them.

I would talk to her about her mother and reassure her her mother will be coming to her soon and ask her mother to call and talk to/reassure her daughter she will be back, etc. too (have her mother make a tape you could play for her?). I would get some of the girl's objects, toys, whatever, from her mother so she could have familiar objects around her too and would just sit with her, not doing other "chores" or activities but just being in the same space as her. If I could sing :-) I would sing children songs she might know or I would read children's books out loud and talk about them as if she were there and a participant (but not ask anything of her). I would not leave her "alone" with her thoughts (and she does have them) but would try to gear most of what I do to doing it "with" her. If she had friends, I would try to make play dates with them, anything from her life she may recognize and enjoy or feel safe/normal around.