I would like to adopt my 14yr. Old niece. She resides with a family in AZ, that her father gave temporary custody to because he lacks a home, food, shelter for my niece. My neices mother is my sister who also is unstable and a recovering addict who was once homeless. I reside in WA state and my niece wants to move into our home with myself and my husband. We have a very stable home, great work history and stable jobs.
Please direct us where to turn, our niece needs us now. She wants to live with us, what action should and can I take to get full custody of her?

The parent is entitled to custody unless that parent is found to be unfit in Court action.

She resides with a family in AZ, that her father gave temporary custody to
What family?Foster care,relatives or..

It depends on the state's law.
Generally the third party may file and/or obtain (for) custody if:
* In the course of a custody proceeding when the judge has reason to believe that neither parent is a "fit" custodian for the child
* When the custodial parent has died and a third party seeks to show the surviving parent is not fit to take custody, or
* When the physical custody of the child has been residing with a third party for a long period.