I have just finished reading Pricness Maria Sergeievna Bariantsky's book My Russian Life and wanted to point out that this is not the Princess Marie Viktorovna Bariantinskaia who is the subject of this thread and was born in 1858. Marie Viktorovna was the aunt of Marie Sergeievna's husband (Prince Anatoli Vladimirovitch Bariatinsky). Marie Viktorovna was Alexandra's Lady in Wainting (according My Russian Life) for the first two years of Alexandra's reign (having been appointed, no doubt, by the Dowager Empress). Marie Viktoria's brother Vladimir (Marie Sergeievna's father-in-Law) was the Grand Master of Marie Feodorovna's court.
I do believe the reference in Alexandra's diary could be to either Marie Bariatinsky assuming that "Olga [her sister-in-law] is refering to Alix's sister-in-law, Olga Nicholaevich. Marie Sergeievna lived in Kiev and had a hospital there and it is possible she would have been familiar with Olga Nicholaevich. However, if the reference is to Marie Bariatinky's sister-in-law Olga, then it is Marie Viktorovna to whom Alexandra is refering. (The younger Princess Bariatinsky did have a sister-in-law named Olga, but not until 1916.) It makes the most sense to me that Alexandra's reference is to the Younger Princess who talks in her book about traveling back and forth from Kiev to St. Petersburg in the spring of 1915.
Ironically, Marie Sergeievna's mother-in-law (Marie Viktorovna's sister-in-law) Princess Nadejda Bariatinsky was made Lady-in-waiting to both Empresses 11/14/1913 on the Dowager Empress's birthday. I believe other members of the family were also ladies-in-waiting.
Marie Sergeievna's Mother-in-Law was killed by the Bolsheviks in 1920 along with her daughter Irene and Irene's husband, Sergei Ivanovitch Maltsov. She does not mention in her book what happened to Princess Marie Viktorovna.
BobG