Certified Contributor II
There are two issues regarding more than one performing artist credits that I seem to come across from time to time. The first is what evidence rises to the level of a credit? Editors seem to have different thresholds in these cases. While this issue may be unguidelineable; nevertheless, no objective guidance makes applicable submissions and error reports difficult.
Consider Remodel by Bernhard Eder
This release was added by an experienced editor and obviously decided that "Tonight, Tonight" and "I Feel You" should not be added on site notwithstanding the co-performer credits on iTunes (the joint credits are also in the autogen notes), deeming the tracks duplicates of recordings already on site.
The second issue is when there is no joint credit on the original release, but later releases of the same recording (e.g. a single, reissue, compilation) do have official joint credits.
As it is my understanding that SHS "errs on the side of inclusion", my position is that we should correspondingly err on the side of co-credits, adding any comments deemed advisable to clarify the entry. If an editor determines that evidence for co-credit is not strong enough, a similar comment should be added to account for that evidence.