Look at these releases: Nabucco and Nabucco: Extraits. The first contains the full performance, the second contains parts, so it is natural to merge the recordings which show up on both releases (these merges are in the review queue). However, the track marks are not completely consistent. It happens that a single track (2.17) of the first release is split into two tracks of the second release (16 and 17) and several times that a single track of the second release (for example 3) is split into two tracks on the first release (1.5 and 1.6).
What is the right way to deal with this situation? From the official style guide, I got the idea that the split parts should be “edits” of the bigger recording. This is what I did. However, now I found that there is also the relation type compilation (which not covered in the linked style guide!), which might be another possibility. As this situation is not too uncommon and easy to define, I think there should be a clear instruction in the documentation what to do (maybe I just missed it).
The way to indicate the relation by the type “edit” does not feel optimal to me. While without doubt, the reduction to a part technically is an edit, it is a very special and basic one. Knowing that one recording is part of another one, it is clear that a lot of info can be transferred from one recording to the other (in particular from the smaller to the bigger one). From the musicbrainz standard to provide the best possible structured data and given the fact that this situation is not too uncommon, I wonder if it would make sense to have a dedicated recording-recording relation type “part of”.
What to do if two recordings overlap, but none is a part of the other one? I don’t have an example for this, but I’m sure that these cases will occur.