What can take the place of a birth certificate?

There is a kid who goes to school with me with no actual birth certificate. The people he lives with brought him into this country from another after finding him on the street or something. No one knows his actual date of birth or where exactly he was born. You need to present a birth certificate to get into school, and I'm told he has a document that takes the place of one. My question is: What do you call this document?What can take the place of a birth certificate?
Look in the real world.

Decode this lyrics " You'll see "

"Wonderful world"

Not grandma and grandpa?

Survivors of " Star on 45"

The original descendant?

Not from Foster home with hear-say only on original descendant?

Not children of "Lady in Red"

Luke 21.30-36

Luke 9.25,55-56,60

Luke 24.44-45,47-48

Luke 3.7-9

Exodus 1.5

What do you think?What can take the place of a birth certificate?
he may be adopted. a new birth certificate

is issued by the US in this case