The reason I left this behavior out at the time is because I thought it would be confusing, but I could be wrong about that.
`try_and_edit` would no longer map to just edit operations, it would also have to enter add-edits and possibly remove-edits depending on how it's implemented. For example, if someone replaces all the instruments on a relationship with different ones, we could either remove the existing one and add all new ones, or edit the existing one to have just one of the new instruments (which one would be arbitrary) and then add the rest.
And if you only add new instruments to a relationship, I wasn't sure if it should just enter the ones you added separately, or also enter edits to split the existing one (which would map to either a remove + adds, or an edit + adds).
This behaviour is used as a workaround for artist-artist relationships where relationships with multiple instruments/vocals might make sense, see linked
MBS-9213. Edit: And this is bad!