How can a child, age 14, continue to live in the custody of relatives in Tennessee?

if the aunt and uncle have legal custody of her than the cant just come get her.if she tries and they have papers from the court than when she comes call the cops and she wont be able to take her.for the mom to get custody back she has to take it to court and if she just started a job and has to live in a motel which in the us its considered homeless.so i dought the judge will favor the mom also the girl is old enough to tell them who she chooses to live wit and why she wants to live with them.and also if they dont have custody of her by law tell them to go file now why she is in thier home.as long as they have had her for a year than they dont need the mothers conscent.believe me i went through this wit my sister.god bless i will be praying 4 u all.