Listing multidisc albums with different composers

[Uoppi]

How can I display multidisc albums as ONE box set in the MinimServer albums list, when the composers differ across the discs? I'm using MinimServer on QNAP with BubbleUPnP Android (in case that it matters).

In other words:
- Brautigam's Beethoven piano sonatas box set shows up as it should: each disc is under one library entry (showing disc 01, disc 02, disc 03 etc.). I even managed to get both the main box cover art and separate cover arts for the discs (nice!)
- Heinz Holliger Edition: I see FIVE separate "Heinz Holliger Edition" library entries (based on the composer). For example, there is an entry "Heinz Holliger Edition - Tomaso Albinoni" where I can see "disc 03", "disc 04" and "disc 05" (which are exclusively Albinoni). I have no idea how to view the Holliger box set as ONE, i.e., so that all the discs display under one library entry.

Is there a tag that could be used? I actually don't mind having the discs split by composer when I'm browsing by Composer but even then, I would expect MinimServer to show an "View all album discs" or "Complete set" option, similar to the "Complete album" option.