When TVDB is working the specials that will match will get the air date and play from On Deck in their intended order. If you’d like to adjust that order change the air date to fit in where you want it and then lock the field.
BTW, those Sherlock Specials are listed and if we’re talking about the same Specials:
A TV Show Library/
…Sherlock/
…Season 00/
…Sherlock - S00E01 - Unaired Pilot
…Sherlock - S00E09 - The Abominable Bride
…Sherlock - S00E20 - Behind 221B The Final Problem
Note: ‘Sherlock - S00E20 - Behind 221B The Final Problem’ is a home grown special special about the making of the final episode recorded from PBS here before the airing of the final episode - and was a major spoiler I would have been wiffed about had I watched it. I recorded the whole thing so I edited out the final episode with VideoReDo, then edited the ‘Special’ into the file above and added the air date to play AFTER the final episode. I’m only just starting Season 2 so the above specials I have will play in their intended (or my intended) order when it’s time for them. I watched the unaried pilot first then discovered the first episode was almost the same thing. Skipped that one and will come back to it later.
TVDB is out to lunch at the moment.