could be a car accident where the mother dies and the daughter is in a coma, at that age she wouldn't have dental records or any records to ID her, probably wouldn't even have a SSN.
so there's a mix up and she's sent to a different hospital then the mother's remains go and the staff has no idea who she is, the red tape that would cause would take months to cut through, government weenies don't exactly move fast and the uncle would probably not push it as he unconsciously wants to avoid seeing his neice's dead body