Series lists sources TVDB/TVMaze

Sonarr version 2.0.0.5338:
Mono version (if Sonarr is not running on Windows):
OS Windows 10:
Debug logs:
Description of issue:

Is there a way to choose where the list of episodes and seasons come from? Their are a few series of shows that the ‘specials’ would be best watched in with the main season instead of as specials such as Bar Rescue and garage rehab. I noticed most lists seem to come from TVDB, but in the case of this show I would like to set it to TVMaze. How can I do this?

all lists

Thetvdb.com is the only source sonarr uses. In addition, for some series thexem.de is used to remap episode numbers.

How do I set up Thexem?