Princess Maria's great uncle Prince Pyotr Dmitrievich S-M 1857-1914 (who was Minister of the Interior in St. Petersburg, Russia, in 1905).
Maria's great-grandfather, Prince Nicolai Ivanovitch Sviatopolk-Mirski, was the last owner of Mir Castle
Princess Maria's Grandparents
Sviatopolk-Mirski family Estate at Vitebsk. The man standing on the left is Maria's grandmother's second husband: Pavel Kondratenko