The plan of the ground floor of the Palace in Mikhailovka

1 - Front Way
2 - Hall
3 - Vestibule
4 - Front Staircase
5 - Reception Room of Grand Duke
6 - Dancing Hall (Ball room)
7 - Gallery (passage)
8 - Drawing Room
9 - Reception Room of Grand Duchess
10 - Room for Needle work (of Grand Duchess)
11 - Boudoir
12 - Bedroom
13 - Dressing Room of Grand Duchess
14 - Working Study of Grand Duke
15 - Billiard Room
16 - Dining Room
17 - Butlery
18 - Room for servants (for those who served at the table)
19 - Gallery of Pompei
20 - Floral Gallery
So, I was not correct in my previous post saying that on the ground floor were only the Main Rooms.
As we see there were the appartments of Grand Duke Mikhail and Grand Duchess Olga there, and the rooms of their suite and their sons were on the 1st floor.