I’ve added a recording which is an arrangement of a classical work (Canon and Gigue in D major, T. 377: I. Canon) with the lyrics from a contemporary work (Song “So Lonely” - MusicBrainz). What should I be doing in this case wrt. linking a work to the recording (or adding a new derivative work)?
I’m thinking something along the lines of this.
looks pretty good to me~
I don’t know about the “arrangement” relationship in this case, mayhaps @Silver_Skree or someone who works with classical works or video game arrangements might know better. for a couple mashups I’ve added, I just used “version of” since I wasn’t too familiar with all the different subtypes.
I do, in fact, work a lot with the “arrangement” and similar relationship types, but that’s almost exclusively for VGM and stuff…
Since MBz has expressly special-cased anything that touches classical stuff, I’m going to abstain on offering any opinion on this, because, as an editor, I don’t want to touch that crap with a nine-foot pole if I can help it, and I have no experience with it anyway 
My best advice is to just interpret and follow the style guidelines with your best judgement, and, at the end of the day, don’t overthink things and do what feels/sounds right and let editors that follow you hash out any technical, pedantic errors.
well, when in doubt, I just add a “version of” relationship, since it relates the two works without implying too much… 
As I understand this kind of MusicBrainz relationships cannot be explicitly defined either way, since media takes many different forms and we cannot really seal them all into some absolute formal frames. So I’d rather perceive those links as “hints” for user to take. It’s not officially provided metadata and it’s not even going to be delivered into the music files themselves when tagged from client side, so you are safe either way 
it’s not tagged in Picard, no… there are many other applications and whatnot that do/can use MusicBrainz data.
also, after reading the documentation, “based on” is probably the right relationship?
This is where the annotations are useful. When a relationship is a little vague, you can fill in some details in the annotations. I like adding all kinds of random knowledge \ links in here. Crumbs for the next user to follow.
