They cannot be found in government databases, they have cover documents since infancy, which are mostly made for intelligence officers and people under state protection. Their dates of birth are known only to their closest relatives. They do not fly on regular flights, they have separate planes. They do not attend kindergartens and schools, they have tutors. They live in residences under the protection of the FSO
Heirs
How Vladimir Putin's Sons Live
https://dossier.center/succession/