Instead of having to decide if our units retain locations or regroup before the game has even begun, it would be more beneficial to have the option alongside Capital movement at the start of a new age.
This means if your units have become stuck in a distant land, or are too sparsely layed out, or you simply want to save on micromanagement, you can choose what you want your units to do at the start of an age.
Regroup and Continuity options can function the same as they currently do, they would simply move to the legacy selection screen.
This also just makes sense from a strategy game standpoint, as we would be capable of commanding our existing military if we were allowed to during the age transition. More control over military commands is more player friendly and enjoyable.
(Bradykin below has a proposal that would also work well to improve control of military units each age transition)