Maternal aunt of the composer (b. 1823), born Yelizaveta Andreyevna Assier (Елизавета Андреевна Ассиер); known after her marriage as Yelizaveta Andreyevna Shobert (Елизавета Андреевна Шоберт).
Yelizaveta was the elder child of Tchaikovsky's grandfather Andrey Assier (1778–1835) by his second wife Amalia Gogel, and sister of the composer's mother, Aleksandra (1812–1854). She married Vasily Shobert (d. 1849), and the couple had four children: Amaliya (1841–1912); Wilhelmina (Vilgelmina); Yekaterina (d. 1866); and Nikolay (d. 1870).
The Tchaikovsky family lived with the Shobert family in Saint Petersburg until the 1860s.
Correspondence with Tchaikovsky
2 letters from Tchaikovsky to Yelizaveta Shobert have survived, dating from 1848 and 1870, and have been translated into English on this website: