Here is synopsis of the FOTR discussion of Bux. from the other thread, didn't mean to shut down that discussion totally, sorry:
FOTR page 68; "Before he left Petrograd, Soloviev apparently was given 200,000 rubles, collected by Count Paul von Benckendorff for the prisoners." [source Bykov, October 17, 1927, in TsDOOSO f.41. op1,d. 129, see also memoirs of Tatiana Teumina on TsDOOSO, f 221,op.2, d. 848 Markov, 228-262; Kasvinov, 309-406.]
"In his book, Benkendorff did not reveal the name of the courier, simply writing that "the money reached its destination, thanks to the devotion and energy of X" [source Benkendorff page 129]
I accept Benkendorff at his word on this. He is a reliable source
" Maria Rasputin later recalled: "Just before the Bolsheviks moved the capital, Boris was in Petrograd to collect a rather substantial sum for Their Majesties. This he did and conveyed it into trusted hands." [source Maria Rasputin, manuscript, in private hands in the United States]
This dates Boris in Petrograd to about early February 1918. Markov confirms meeting Soloviev at Vyroubova's flat at this time and states "Soon after this he departed for Tobolsk with some things for Their Majesties." @ pg130. HOWEVER, on pg. 131, Serge Markov goes on to say that he forged travel documents in the name of SOLOVIEV. "I typed in this name and went to Madame Vyroubova and proudly displayed my new "papers." She gave a cry of horror. "Whatever have you done Serezha? Solov'ev is the name of Rasputin's son in law." I had never thought of that, but now that the form was already filled in, I could not alter it. @pg 131.
Now, Nicholas Markov (no relationship to Serge M.) was an avid monarchist working to assist the Imperial Family. His deposition to Sokolov:
Some time later another officer left for Siberia, Serge Markov. He had ties to Dehn and Vyroubova and was sent by their wishes and at their expense. As our organization had little money, I took advantage of his leaving to task Markov to look up N**, to make contact with him and to inform us of his work. ...
In spring 1918, officer S. Markov returned to Petrogard. He told us that in Tyumen, Rasputin's son in law Soloviev was the head of Vyroubova's organization, and that he had been charged with the health of the Imperial Family and that the presence there of our officer N** was, to say the least, undesirable. ...
S. Markov was someone I did not really know personally and so I followed the opinion of Dehn, it seemed to me upon his returm from Siberia that in hindsight: his tales inspired little confidence in me; he was not very convincing. Personally, he gave me the impression of a young man audacious in excess, and greatly avaricious when it came to money.
(According to Victor Sokolov, one of the Vyroubova "team"): In the end of March or early April 1918 Markov returned. He told us that in Tobolsk he met with enormous forces, entire cavalry regiments which were ready to save the Imperial Family at the first possible moment, and they occupied the central positions and that at the head of the entire matter was Soloviev. ... After some research, it was clearly and entirely under the orders of Soloviev that he had learned of what had gone one before and that he directed all of his movements. I give absolutely no credence to the tales of Markov; they have no measure of truth."
" Soloviev was back in Tobolsk on February 21, when he turned over the 200,000 rubles to a certain "Mademoiselle X, a lady of the court," as Serge Markov called her. This mysterious woman was, Markov said, ill at the time the Romanovs were originally sent to Tobolsk, arrived at a later date, but "the guards refused her entry to the Governor's House" She lived in her own apartment in town" [source Markov 212]
Markov pg 211 says Then I hurried to a house where I had reconnoitred by daylight, where Mademoiselle X, a lady of the Court, was living. At the time Their Majesties had had to leave Tsarskoe Selo, Mademoiselle X was ill; when she followed them to Tobol'sk the guards refused her entry to the Governor's House, so she was waiting in Tobol'sk unti the committee changed its mind. She was loyally devoted to Their Majesties, and enjoyed their confidence and regard. She had never met me before, and was surprised that I had come on behalf of Madame Vyroubova, from whom I brought a letter to her, whereupon her alarm changed to pleasure. She thanked me and at once declared her willingness to deliver to Their Majesties the parcels I had brought with me, without exciting remark. She hoped to accomplish this by means of the valet Volkov, who had free access to the house, and with whom she was in touch. I left money and letters with her, which she promised to give Volkov next day. We made arrangements for a meeting the following evening and I went home full of bright hopes."
"Markov clearly meant Baroness Sophie Buxhoeveden, the only "lady of the court" who had not joined the imperial family due to illness, who later came to Tobolsk; who was refused admission to the Governor's House' and who had her own apartment in the town." [no source] Buxhoeveden does seem to fit the description, and pretty much nobody else does.