The Importance of Birth Certificates

What happens when the police raid your house only to find a locked door, which opens to reveal a 14 year old inside? The suspect claims the boy's his nephew but can provide no birth certificate, school records, proof of guardianship, or any other form of ID? Add in a headmaster under fire and death eaters out to cause mischief? Answer: trouble, with a nice dash of chaos. Set in GOF