Okay, I've been looking for a mod where you can "summon" Gormlaith as a follower, and found one mod that was made (two?) years ago or so. However, he used the wrong ID.

Gormlaith has three base IDs, because there's cutscene, sovngarde, and thu'um Gormlaith. Gormlaith's base ID for her shout (ghost like) form is 923FA, and the one I want (the one you see at sovngarde) is 44236.

The problem is that Gormlaith 923FA is the only one of the three that acts as a follower and follows you around. Gormlaith 44236 stands there, or engages any foes (like dragons). However, if anyone creates a mod (I don't know how) I think it might be best to make a fourth instance of Gormlaith with a fourth base ID that essentially copies the 44236, and binds her as a follower, like Lydia, so that it doesnt bug the main campain out.