Eleanor Roosevelt was very upset that she was informed so late, but with the help of the Mansion staff (about thirty people during the Roosevelt Administration) and especially the three major staff members she was able solve the problems satisfactorily.
Those were the Butler Alonzo Fields,
the housekeeper Henrietta Nesbitt
and Chief Usher Howell Crim, who had the most important job, as he had to oversee the reception and housing of heads of state or government, diplomats, and other guests of the White House.
BTW: Roosevelt liked the idea with the map room. In January 1942 already, FDR converted a White House basement cloakroom into a top secret communications center and map room.
In this undated photo, military personnel are shown in the White House Map Room.