The First Space Lord was a member of the Manticoran Admiralty and the senior uniformed officer of the Royal Manticoran Navy.
The obvious choice here is for Hamish to drop back into uniform. Double hat for a while ala Thom Theisman until they can decide who can drop into one of the jobs.
The Second Space Lord was one of the Lords of Admiralty who controlled the Royal Manticoran Navy, responsible for handling operational and tactical planning. He or she was also the head of the Office of Naval Intelligence and the Bureau of Planning.
Multi-hatting again. Honor would be my suggestion here, and have her remain as commander of home fleet.
Of course these choices potentially do run into the issue of married and in the came command.
The Third Space Lord was a member of the Lords of Admiralty that controlled the Royal Manticoran Navy, in charge of the Bureau of Ships.
The holder of the office oversaw all construction and maintenance in association with the fiscal directions of the Second Lord of the Admiralty. The major space stations in the Manticore System as well as the dispersed yards in planetary orbits were under his or her control.
Admiral Sir Craig Warner, assuming he survived of course.
The Fourth Space Lord was a member of the Lords of Admiralty that controlled the Royal Manticoran Navy, in charge of the Bureau of Weapons.
As such, he or she was responsible for the research and development of new systems for the Navy. (HH9)
Admiral Hemphill
The Fifth Space Lord was a member of the Lords of Admiralty who controlled the Royal Manticoran Navy. The Fifth Space Lord was responsible for the Bureau of Personnel (BuPers for short), which handled recruitment, training, and personnel assignments for the Navy.
Admiral Khumalo. Double hat Mike with Talbott Station command and 10th fleet command.
The Sixth Space Lord was a member of the Lords of he Admiralty who controlled the Royal Manticoran Navy. The Sixth Space Lord was responsible for the Bureau of Training (BuTrain for short), which handled the training and education of naval personnel in accordance with the Third Lord of Admiralty.
Khumalo again, but have Captain Shaw actually run the thing, probably with a promotion, and in due course, to take over outright.
The Seventh Space Lord was the seventh most senior uniformed officer of the Royal Manticoran Navy, holding the offices of Surgeon General of the Star Kingdom of Manticore and head of the Bureau of Medicine.
Around 1920 PD, the position was held by Vice Admiral Allen Mannock. (HH9)
Fritz seems an obvious choice, though I'm sure there are lots of administrators, and doctors, who could fill the spot.
Sarnow is too important where he is to drag back, similar to Mike.
Alice is better off where she is, and likely for the next fleet command anyway.
Hard to think of who else is alive lol.