Putin's and Kabaeva's sons registered under a different surname: what is it

According to the data contained in the book 'The Tsar in Person', it has been revealed that Vladimir Putin's and Alina Kabaeva's children use the fictitious surname Spyridonov. This is likely related to parental connections.Putin's daughters from his first marriage, Katerina Tikhonova and Maria Vorontsova, also use fictitious surnames. It has been found that this may be related to family ties on both paternal and maternal sides.Most of Putin's and Kabaeva's common children spend time in the Valdai residence, where comfortable conditions have been created for them. Despite the fact that the children rarely appear in public, they are under constant care and protection.The investigation also revealed another secret daughter of Putin, Katerina Krivonogikh. These facts arouse some public interest regarding the personal life of the Russian president and his children.