]I don't understand the reason for the Question?
It's pretty straight forward, would Ben Sisko's personal information include the name of his birth mother.
I would imagine that Sisko would have a relative high Starfleet security clearance. Modern day this would involve at least a cursory look at the parents, siblings, spouses, etc.
Even if he had never seen his own "birth certificate," it kind of hard to believe that Sisko had never seen his own general records, if only to confirm their accuracy.