In the case of SNW, she's at the end as "And Rebecca Romijn". Not quite like the 70's and 80's show where a bigger star was listed last as "Also Starring....". After Anson and Ethan, it does go alphabetically, until Bruce Horak comes after Babs Olusanmokun, so it kinda falls apart there.
Normally comes down to who has the better agent. ETA: Which explains how she got the 'And...' All the best agents ask for or demand those.
That's because Horak is technically a guest star, he'd be dropped from the credits when he doesn't appear. And the Romijn comes at the end no matter what.
I don't think it works that way, exactly. Guests and occasional characters usually aren't billed in the weekly intro, unless - as noted above - their agent negotiates a special billing for them, in which case they still wouldn't end up in the alphabetical cast list. They get something like "Special Appearance" or "Featuring," and sometimes in the credits that run at the top of Act One rather than in the intro. Long Wikipedia article on billing behind this link
I expect they are using the same rules as the Discovery credits, doesn't that have actors appear and disappear from the opening credits?
If only that were true. Perhaps you have forgotten, they browbeat Enterprise producers into changing its theme, (to something worse) and adding "Star Trek:" to the title.
I'm worried that the Cerritos crew are going to mess it up drawing it somehow and I don't even want to know what the Protostar crew are going to end up with.