Continuing Characters In Future Histories?

A future history does not need any continuing characters. Its unity is in events, not in individuals. In Heinlein's Future History, Harriman and Libby each appear twice as does the crew of the Vanguard and that is it. I thought that a committee chairman had been named in two stories but can't find him on looking through the texts.

I think that a spaceship captain named in the early interplanetary period should have been retrospectively recognizable as an earlier alias of Woodrow Wilson Smith/Lazarus Long but that did not happen. Some characters achieve historical status by appearing in only one story: Dahlquist; Rhysling; Long. Another, Scudder, does not appear in any of the stories.

Anderson's Psychotechnic History follows Heinlein's model:

Fourre appears twice and becomes a historical figure referred to later;
Trevelyan Micah appears twice;
in both cases, as with Heinlein's Harriman, the story set earlier was written later - the author filled in the character's earlier history.

In Anderson's Technic History, the situation is reversed. A casual reader might think that this future history is merely two series about individual characters, van Rijn and Flandry, although there is in fact far more to it than that.