According to the old family legend prince Michał Kazimierz Radziwiłł Rybeńko
had two sons. When the times of partitioning was nearing affraid of
family and his heritage he has hidden both of them in the conspiracy.
The older one was sent on the province to be growed up by the monks. The
younger one landed on... the Russian throne.
The change has, accoriding to legend, taken place in Szczecin when
Czarina Catharina was visiting her family city. We do not know if it was
acctualy the exchange or younger Radziwiłł was a gift to the Russians.
This family legened would be maybe only a legend, a fairy tale for the
childrens if not a blatan similarities between Czar Paul I and Marcin
Mikołaj Karol Radziwiłł. What you can observe on portraits of both.