Premise: The Lopukhin family was a noble family of the Russian Empire, forming one of the branches of the Sorokoumova-Glebov family. One of its members, Eudoxia Lopukhina, married Peter the Great. When Pyotr Lopukhin's son died childless, the family's princely title passed to
Hypothesis: Pyotr Lopukhin had a son who had four children.