I've had another thought overnight (I'm allowed one a day).
Dorothy Dunnett stopped at the accession of Elizabeth I, or thereabouts - but what would have happened to the Lymond line after that?
I can see someone young, blond and incredibly gifted in military strategy leading a company of mercenaries through the Thirty Years War, and another descendant getting involved with the '45 Rebellion (and probably escaping over the heather by the skin of his teeth back to Sevigny), or embroiled in the French Revolution (again escaping by the skin of his teeth).
Does anyone have any other ideas?
"There were no full time Vikings back then. Everybody had another job."
Neil Gaiman, from Odd and the Frost Giants.