HAHAHAHA, I can add it as a regular JUTSU, thank Go..Buddha-sama.
And his family is the group of mercenaries he joined. Fearing to lose them IS what made him leave them. 
[s]
As for information on family members, he checked the "Orphan" box on the document. As for legal guardian, he raised himself...damn he's looking like a spy more and more. 

How about this. The Anbu captured him and performed interrogation on him by genjutsu and whatnot, then allowed him to enter the academy after wiping memories of interrogation. Nah, then they would find about his real past...[/s]

He forged the documents and arranged for an elderly couple to adopt him.
I'll just put their names AS LONG AS YOU KNOW that their NOT the real names.