At present we can easily merge a single disc release into another single disc release in a single edit, either resulting in a "merged" single disc release or a multi-disc release by "appending" the medium to the next position. However, to merge a single disc into a multi-disc release, where you want the medium from the single disc to be merged into an existing medium in the multi-disc takes two edits (if it's not the first medium you intend to merge): you need to first shift the medium position of the single disc and then do an ordinary merge. The problem is that this first step is slightly odd (shifting a medium to an arbitrary position in an apparently single disc release), both in that it is not obviously intuitive to new editors and in that non-auto-editors have to get this odd edit accepted first before they can do the merge which is both problematic in that they may have to wait up to two weeks before they can do the next step and it's difficult to explain clearly to voters what their intentions are.

I propose that the merge releases function should support the appending of a single disc release into a multi-disc release with the option of placing the medium from the single disc release in the same position as an existing medium in the multi-disc release, resulting in those mediums being merged.

The Merge Strategy: "merge mediums and recordings" option should present the list of mediums (like the append option) if the target release is a multi-disc release, thus giving the option to select any one of the mediums in the multi-disc release as the target medium for merging the single disc release into the multi-disc release.

(This was previously discussed on IRC here: http://chatlogs.musicbrainz.org/musicbrainz/2011/2011-08/2011-08-11.html#T14-16-28-392050)