So whenever the “A” listers are away, not far away are a group of NPC’s & secondary characters taking care of every day business. Including: but not limited to making a secure base camp for the exploring group.
Likewise if you wanna change out a character for a story ARC I have no objection really provided you recall these secondaries will be a few paces behind the principles. Don’t under-power the party is all I am saying.
Ideally I want everyone to have at least one and maybe up to three Back ups at least partially created – just-in-case- So give them a look over once in a while as it could save some valuable game time if you are at least partially pre prepared!