Here’s me putting this into action:
https://www.musicbrainz.org/series/86d65955-a4af-4f2a-8f92-2106665ae872
This catalogues all the releases of the game music from the franchise Super Smash Bros., which you will linked as a series relationship.
This edit merges the release group of the official CD release and someone’s bootleg gamerip into one which would then be part of the release group series above.
https://www.musicbrainz.org/edit/72088302