My question involves guardianship in the State of: South Carolina. My mother lost custody of all 3 of her children in 2003. My brother and I went to live with our grandmother on our fathers side. My little sister went to live with her father. He recently passed away and the papers say in the absence of him, she would move back in with our mother. His death was a sudden accident and he left no other arrangements. Mother is still unfit and my sister says she wants to live with us here. She has spent every weekend, school break, summer, Christmas, etc here with us. Can I at 17 take legal guardianship over her?