I.N.-- Here are a few more:
1st row: the name to the right of "Pavlov" is Dzhurkovich (Jurkovic), the Grand Duchesses elusive "Little Montenegrin".
He's the younger man standing to the left of their photo on the wall.
2nd row: the second name to the right of Baron Taube's is Baron Shtakelburg.
Thank you father Nikolai! And a few more from me-
Third row, left (probably this man sitting on an armchair): Trofimov
The name after Nikiforov is Chernov (I think)
So we have:
1) Syroboyrsky, ?, ?, Pavlov, Jurkovic, M?, Z?
2) Pokrovsky, Vinogradov, baron Taube, ?, baron Shtakelburg
3) Trofimov, Nikoforov, Chernov, ?
4) ?, ?, ?, D?