She's not credited as a main cast member (she's not credited at all), hence she shouldn't be added to the show's regular cast. She needs to be added as (uncredited) to the episodes where she appears.

If it helps- from what I remember she appears in all 5 episodes, but that's just from memory so would need to be verified.

@ReticentRobot said:

If it helps- from what I remember she appears in all 5 episodes, but that's just from memory so would need to be verified.

Yes, she does. Briefly, but in every episode, so I added her to all episodes as uncredited. I assume she was not credited because she didn't have any lines.

That makes sense! Thanks for updating.

Am I supposed to close this? I don't see how if so (on mobile).