Linking Acapellas to Originals

I recently asked a similar question about instrumentals and while at first I thought it was a bit odd that “instrumental of” was a recording-work relationship and not a recording-recording relationship I have since gotten used to it.

So what about acapellas? Why is there no recording-work relationship for those? It would make sense to me if it was the same relationship type as for instrumentals, but I didn’t find any relationship for it anywhere. Btw is it just me or do searches in the documentation never yield any results?

If you’re talking about hip-hop acapellas, I’d use the ‘edit’ relationship to link the acapella version to the original. Like instrumentals there’s also a ticket proposing a new ‘acapella’ relationship.
STYLE-805: Add recording–recording “is the a cappella version of” / “is the album version of” relationship

I would link as partial recording of work, until there is a more specific attribute.
But acappella recorded songs is surely rare compared with instrumental versions of songs.