Where can I get help for a sibling if a troubled child?

[OzarksGrandma]

My 13 year old granddaughter is having a lot of problems dealing with her eight-year-old sister. The story is too long to go into on a forum, but basically the eight year old had been physically abused by the non-custodial father. She is now tied up in the foster care system but we are very close to getting her returned to our family.

We now have unsupervised weekend visits, but she is so traumatized by what she's been through that she wreaks havoc on our household. Because she technically is in the foster care system now our hands are tied to get her the proper care that she needs. Hopefully it will not be very long until we can do more for her, but right now I am worried about my 13 year old granddaughter.

I was hoping for suggestions on books that my 13 year old granddaughter can read to better help her understand how to deal with her little sister's outbursts and aggression. She is extremely intelligent and a total bookworm, but I'm having trouble finding books geared towards young teens to help her.

Thank you in advance, and I hope there are some good suggestions out there.