Complex sentence: Alexandra Alexandrovna Pistohlkors, (1888--1968), née Taneyeva, was the younger daughter of noted Russian composer Alexander Taneyev, sister of Anna Vyrubova, and wife of Alexander Erikovich Pistohlkors, who was the stepson of Grand Duke Paul Alexandrovich of Russia.
Split into simpler sentences: Alexandra Alexandrovna Pistohlkors ("née" Taneyeva; 1888--1968) was the younger daughter of noted Russian composer Alexander Taneyev and the sister of Anna Vyrubova. Her husband was Alexander Erikovich Pistohlkors, who was the stepson of Grand Duke Paul Alexandrovich of Russia.