Let's not lose sight that "family scouting" remains pure and the unadulterated double-speak of promoters too chicken to say "BSA 4 girls in its 4th generation." As a result, we become the beneficiaries of unintended consequence -- like this back and forth about who gets invited to what activities.
Is "linked troops" a buzzword for coed? Some troops will take it that way. National is still keeping up appearances that CoEd is not an option for troops. How that holds up will depend on how we on the ground react when one of us has a tight-nit patrol of sharply uniformed boys and girls wanting to stick together.
I guess we'll see how it plays out. There are two sentences there that could be interpreted in different ways.
So any unit serving females (girl pack, family pack, girl-only scout BSA unit, or co-ed Crew, Ship, or Post) must have a female adult registered leader. I agree this is unit specific.
It's not clear to me that this statement is unit specific. If the registered female cub is at the activity it seems like it would trigger the adult female over 21 requirement. I suppose one could argue the tag-alongs aren't "involved" but that feels kinda weak to me.
No, again, the OP asked about a registered female cub that was a tag along. G2SS refers to members of the troop (e.g. your quote, "every unit serving females)." A tag along, even one registered as a female cub, is not a member of the troop.