Catherine Adolphovna Schneider (Russian: Екатерина Адольфовна Шнейдер born Henrietta Catharina Luisa Schneider; 20 January 1856 – 4 September 1918) was a tutor at the court of Tsar Nicholas II and Tsarina Alexandra.
 She taught Alexandra Russian before her marriage, just as she had some years earlier taught Russian to the Tsarina's sister, Grand Duchess Elizabeth Fyodorovna before her marriage to Grand Duke Sergei Alexandrovich of Russia.
Grand Duchess Anastasia Nikolaevna of Russia (Russian: Анастасия Николаевна Романова [Anastasia Nikolaevna Romanova]; June 18 [O.S. June 5] 1901 – July 17, 1918) was the youngest daughter of Tsar Nicholas II, the last sovereign of Imperial Russia, and his wife, Tsarina Alexandra Feodorovna.
The Khodynka Cup of Sorrows, also known as the Coronation Cup, the Sorrow Cup, or the Blood Cup, was made for the coronation of Tsar Nicholas II and Tsarina Alexandra Feodorovna in 1896.
 The cup bears the cyphers of Nicholas and Alexandra surrounded by a geometric pattern with the Romanov eagle on the opposite side.
Maria Rasputin (baptized as Matryona Grigorievna Rasputina) (26 March 1898 – 27 September 1977) was the daughter of Grigori Rasputin and his wife Praskovia Fyodorovna Dubrovina.
 She wrote two memoirs about her father, dealing with Tsar Nicholas II and Tsarina Alexandra Feodorovna, the attack by Khionia Guseva and the murder.
 A third one, "The Man Behind the Myth", was published in 1977 in association with Patte Barham.
 In her three memoirs, the veracity of which has been questioned, she painted an almost saintly picture of her father, insisting that most of the negative stories were based on slander and the misinterpretation of facts by his enemies.
Grand Duchess Tatiana Nikolaevna of Russia (Tatiana Nikolaevna Romanova) (Russian: Великая Княжна Татьяна Николаевна) (10 June 1897 – 17 July 1918) was the second daughter of Tsar Nicholas II, the last monarch of Russia, and of Tsarina Alexandra.
 She was born at the Peterhof, Saint Petersburg.
Ceclava Czapska ("Cécile Czapska") (Bucharest 2 January 1899 – 1 December 1970) was a Romanov impostor who claimed to be the Grand Duchess Maria, daughter of Tsar Nicholas II, the last autocratic ruler of Imperial Russia, and his wife Tsarina Alexandra.
Nicholas and Alexandra is a 1971 British biographical film directed by Franklin J. Schaffner and written by James Goldman, based on Robert K. Massie's book of the same name, which partly tells the story of the last ruling Russian monarch, Tsar Nicholas II of Russia, and his wife, Tsarina Alexandra.
Suzanna Catharina de Graaff, born Suzanna Catharina Hemmes, (5 May 1905, in Rotterdam – 25 November 1968), was a Dutch woman who claimed to be a fifth daughter of Tsar Nicholas II and Tsarina Alexandra.
 Her claim was accepted by Anna Anderson, who claimed to be Grand Duchess Anastasia Nikolaevna of Russia, but by few others.
 The Russian Imperial family was killed by Bolsheviks in Ekaterinburg, Russia, on July 17, 1918.
 After the reported murders, a number of people claimed to be surviving members of the family.
Anna Anderson (16 December 1896 – 12 February 1984) was the best known of several impostors who claimed to be Grand Duchess Anastasia of Russia.
 Anastasia, the youngest daughter of the last Tsar and Tsarina of Russia, Nicholas II and Alexandra, was killed along with her parents and siblings on 17 July 1918 by communist revolutionaries in Yekaterinburg, Russia; but the location of her body was unknown until 2007.
The Russian Imperial Romanov family (Tsar Nicholas II, his wife Tsarina Alexandra and their five children Olga, Tatiana, Maria, Anastasia, and Alexei) and all those who chose to accompany them into imprisonment – notably Eugene Botkin, Anna Demidova, Alexei Trupp and Ivan Kharitonov – were shot, bayoneted and clubbed to death in Yekaterinburg on the night of 16-17 July 1918.
 The Tsar and his family were killed by Bolshevik troops led by Yakov Yurovsky under the orders of the Ural Regional Soviet.
 Their bodies were then stripped, mutilated, burned and disposed of in a field called Porosenkov Log in the Koptyaki forest.

Question: Suzanna Catharina de Graaff's claim of being the fifth daughter of Tsar Nicholas II and Tsarina Alexandra, was accepted by one of several imposters who clamed to be who?
Answer: Grand Duchess Anastasia of Russia