Currently, the guidelines are silent on the following situation:

Artist B records a track.
Artist A remixes the track and puts it out on a release.
The release is credited to artist A, and the remix track is not visibly credited on the release.

I propose that artist B be credited at the recording level, and performer and remixer relationships be added to the recording. At the tracklist level, artist A should be credited.

This is consistent with how we take the album artist as an implicit credit for tracks on the release unless there is an explicit credit given to the contrary. Additionally, it allows us to store multiple pieces of information: how the release is credited, and who the original artist is. This information will also be presented on the release page through the relationships.