Just some additional information on Princess Tatiana Yussupoff:
Spending several years in Russian archives, working on Felix's documenatl biography, I was surprised to see how little information is available on his aunt Tatiana, who died in 1886. Her destiny was not a subject of my research, but since I began my research from the wedding of Zinaida Yusupoff to Felix Sumarokoff-Elston, I had to read some correspondence of Zinaida related to her youth.
It was very interesting to see that in all family archives there were only 3 pictures of Tatiana, whose family nick name was "Tanyok" or "Aunt Tanyok" (Танек or тетя Танек). One was a portrat of Tatiana in her teen years (published on this forum yearlier) that Zinaida kept all her life in her study in Arkhangelskoe, one picture of Tatiana with her sister and nepfew Nikolai and another one was a photo of Zinaida (8-9 yers old) with her sister in Vienna.
Then one day, in Russian Historical archive I met a historian-amateur, who was trying to find out the reason of such mistery around Tatianas's name. As all girls of her epoch she kept an everyday diary and the strange thing was to see that in her last diary-book there were missing (ripped off) all pages with the notes on the last weeks of her life. That pushed this historian to read her previous diaries during the 1885-1886.
His research only confirmed the idea that Yussupoff's family was surrounded by a mystery.
Apparently Tatiana was madly in love with a young man called Paul, who was living in the nearby estate... (Well, could have it been be handsome Grand Duke Paul Alexandrovich?)
Then, everyone in Arkhangelskoe village, who knew the whitnesses of her grave opening by the bolsheviks, said that when the grave was opened there were found not only a woman's body but also a body of a baby (Who could have it been? Her baby brother Boris...or her own child?
?)
The other old-timers of Arkhangelskoe claimed that locals insisted that the young princess drowned in the river...
The only thing I could add from what I read myself from the Yussupoff archives, that whatever was a real reason of Tatiana's death, the day of her death Zinaida always comemmorated by spending whole day in the church.