Indeed, every time we "join" them (at the starts of specific adventure runs, thus TMP, TWoK, TFF and TUC), we are left wondering which of them were there already, and which just joined the preexisting team.
In TMP, there is an emergency, and we see most of the usual suspects on the bridge - but only after the emergency is declared, so perhaps they were summoned to turn a refit crew into an operational one. In TWoK, there's this birthday cruise, preceded by the Kobayashi Maru test where it already appears that something unusual is going on, else why would all these Commanders be attending it - so probably the old folks are gathering around Kirk rather than around the Enterprise. TFF more or less immediately follows the public trial where the heroes were told to go fly the Enterprise again (and not get into public trouble again), so they probably wouldn't say no quite yet. And TUC is set up by Spock, presumably because he is well aware he can't trust most of the top officers and needs the Old Team around him.
Now, which of the folks are married to the ship on each occasion? Scotty very well might, on all of them. And perhaps that makes sense, if ships are individuals and it takes an expert to tend to each. Apart from that, though...
Timo Saloniemi