I started a new submission and then realized that I should ask this question first, since I'm not sure that the related FAQ answer directly relates to this kind of example: When submitting a listing for an original (before submitting a later cover), would it be better to always submit the chronologically first release, or would it be better to submit the original (demo) version/recording (by a different artist) if it was indeed released later?
The specific example here involves the work of the late António Variações and the subsequent supergroup Humanos: Many years after his death, some unreleased songs were uncovered (including some demos)--and Humanos was formed specifically to perform and officially record those songs. A couple of years after that, though, a new overall compilation for António Variações included some of those demo recordings.
Therefore, should the submitted original here be for Humanos (since their version would've been the first release) or for António Variações (since his demo was the first version and was eventually released)? (In either case, I was ready to then submit a newer cover by a different artist.)