However the only way to add him to the relevant eps would be to open each one.

Yup, that's the only way. There is no hidden bulk edit feature for adding/removing guest star credits.

For instance, in https://www.themoviedb.org/tv/64432-the-magicians/season/4/episode/7?language=en-US it was revealed that Mageina Tovah's https://www.themoviedb.org/person/20645-mageina-tovah?language=en-US character is named Zelda.

I'm not 100% I understand what the issue is. You can edit the current character name as long as Zelda is not a spoiler (one edit).

@banana_girl said:

Yup, that's the only way. There is no hidden bulk edit feature for adding/removing guest star credits.

Thanks, will take a run at it some time.

For instance, in https://www.themoviedb.org/tv/64432-the-magicians/season/4/episode/7?language=en-US it was revealed that Mageina Tovah's https://www.themoviedb.org/person/20645-mageina-tovah?language=en-US character is named Zelda.

I'm not 100% I understand what the issue is. You can edit the current character name as long as Zelda is not a spoiler (one edit).

AFAIK you can add the character name on an episode basis, but this is not reflected throughout the series. e.g. If someone mistakenly added Ethan Peck's ST:Discovery character as Dr. Spock for one ep, it wouldn't change that in previous eps. It's different for season regulars. Guess it's just my OCD! There have been a few times when I've got twitchy and wished I had the time to go and correct historic inaccuracies. There's an example in Rizwan Manji's credits if you look at Flash Forward. The same character is listed as FirstName and FirstName Surname.

 If someone mistakenly added Ethan Peck's ST:Discovery character as Dr. Spock for one ep, it wouldn't change that in previous eps. It's different for season regulars.

You're right it wouldn't. We support multiple character names, but they can't be edited like single characters. Series regular credits works the same way. I re-added Rizwan Manji's incorrect credit using the right character name.

@banana_girl said:

You're right it wouldn't. We support multiple character names, but they can't be edited like single characters. Series regular credits works the same way. I re-added Rizwan Manji's incorrect credit using the right character name.

Cheers! I just checked the changelog for the show - that example was the first one I found by clicking through the likely suspects in the cast of The Magicians and not a pointed one!

If no-one else beats me to it I'll take a run at Jim Beaver/Supernatural S14 sometime soon.