my own DD now 27 came to me when she was 14 and very sick. Her bio mom was very blaise' about the whole thing. Told me this kid was manipulating folks to tell them how sick she is, and if I wanted to step in, go for it, but dont look to her for help. DD spent about a month in and out of the MD offices, and hospitals before we finally got her stable enough to eat. She was 78 pounds and 5'6" it was painful to watch. She would ask me as the years passed why her mom was the way she was. I encouraged her to love her mother, but dislike the mothers actions. To enjoy mom while she was sober, stable and active, but to not be heartbroken when she disappeared again, or snapped and said hurtful things.
it took many years for DD to trust bio mom, and start to understand that this woman was unstable, and not able to care for herself. It was DDs lesson to learn. I could only hold her hand while she figured it out.
I ask you to consider aiming this child towards love. Speak to her and tell her that real mom is trying very hard to say things that will make up for the hurt of not being around for many years. That we dont always have to believe everything that everyone says, and no matter what YOU are standing right there. It will be ok no matter what happens. DD said she used to become so excited when mom would show up and make promises, and ask for forgiveness, but after a while it just got to be more of the same sad song, and she learned quickly that mom was temporary.
Can you speak to bio mom? Can you let her know that this child IS excited to see her, but there is no need to go over board with promises that cant be kept? That to have her here for today is enough, she doesnt have to promise a tomorrow. Perhaps if she can deal just one day at a time she can offer at least one stable day. If she isnt willing or able, perhaps you can simply prep this child that for today bio mom is here. its really really really hard not to want to go slap the snot out of this woman, trust me I know. Its so much better for YOU to be the one grown up this kid can count on. As long as bio mom isnt fighting for custody, then the best you can do is be supportive and be a safety net.
This mom will most likey spend a few days or weeks hanging around, and the grow weary of it, and go away.
Im rooting for you.