Manually add extra episodes

I understand you need to follow the procedures for adding episodes into Plex.
So…
I’m trying to add episodes of the old 1963-1989 Dr Who, in particularly in season 5.
In The Wheel in Space, it has 4 episodes. IMDb shows it as 4 episodes being 37 to 40.
But…
Because it’s a television show known for having lost episodes, enthusiasts have lovingly recreated episodes. Though some have required more than 1 episode.
The example I give started with 4 episodes, but now is presented with 6.
Can I add these extra episodes?
Or does the programming lock in with the exact numbers as shown on IMDB?
Any help is greatly appreciated.

Best check if those episodes are officially listed on TheTVDb or TheMovieDatabase
If they don’t you could add them as local extras to the show or season – this way they’ll still show alongside the official episodes but are not part of the official sequence (you’ll also only get the title based on a file name – no metadata etc.)

Thank you for the quick reply. Will they still be in order? As in, can they be part of Season 5 as opposed to being put into a separate section, such as Special Features?

If they’re listed on one of those sources, you can name them as regular episodes and Plex will recognize them as such. Keep in mind Plex is not matching those episodes against IMDb!

The example you gave is listed as regular episodes on both sources (s05e35-e40):

Long story short… just name those as you named your other episodes and they will show up alongside all those other episodes.
Example:

TV Shows
  Doctor Who (1963)
    Season 05
      Doctor Who (1963) - s05e35 - The Wheel in Space (1).ext
      Doctor Who (1963) - s05e36 - The Wheel in Space (2).ext
      Doctor Who (1963) - s05e37 - The Wheel in Space (3).ext
      Doctor Who (1963) - s05e38 - The Wheel in Space (4).ext
      Doctor Who (1963) - s05e39 - The Wheel in Space (5).ext
      Doctor Who (1963) - s05e40.ext     <- actually no need to include the episode title in the file name

Where .ext is your respective file extension.

If you have files that do not show up on those repositories you can name them as local extras.
FAKE example, assuming you have the full video in a single file:

TV Shows
  Doctor Who (1963)
    Season 05
      Other
        The Wheel in Space.ext

This would show as an Other type local extra in Season 5. Keep in mind most Plex clients are currently not able to display those – you’ll pretty much only get season-level extras to show on iOS and mobile Android platforms (though Plex is recognizing them alright and Plex are working to bring support for local extras to other clients)