Oh good lord. ANYONE who harbors this child if she runs away may face CRIMINAL charges, and severe ones at that.
Until she's legally able to leave home and fend for herself, Mom & Dad rule the roost and what they say goes; if they want her home, she goes home. It really is that simple.
End of story. Even if.
SHE certainly cannot change custody or arrange guardianship herself - she has no legal standing to do so.

