As always: look up these episodes on either TheMovieDB.org and/or TheTVDB.com
Whether (and how) you find them there, determines how you add them to Plex. (i.e. as a separate show or as special episodes. In the case of specials, it also determines which episode numbers you need to give them.)
Don’t forget that there can be differences between TheMovie DB and TheTVDB in how these episodes are numbered and sorted. In order for Plex to add them as you expect, edit the show and set its “Episode Ordering” to the suitable option.
After a mismatch it can be necessary to perform the Plex Dance, so that Plex will forget the match of previous attempts.
