I sort my music by path via virtual tag "$Split(<Path>,\,4)" and use Album Cover view. This works exactly how I want, as it displays my music in the exact order that they exist as in my folders.
The way it sorts my library also splits discs into their own entities.
I'm looking for a method in which I can manually select specific discs to "merge" into a single entity.
Below I've tried visualizing how I want to combine the following albums:

The red square outlines indicate the parent directory, and the red circle outlines cover the specific discs I want to have combined into a single entity.
For example, Pokemon Ruby/Sapphire includes all 4 discs within the square outline, however I only want the first 2 discs to be combined, with the latter 2 remaining as separate discs. I only want the first two entities of Pokemon HeartGold to be combined, with the third disc being separate. And, I want all 4 entities of Pokemon Black & White to be combined into one.
I'd like to be able to highlight the specific discs and right-click > edit and select "merge (internally)" for them to merge (WITHOUT MODIFYING ANY FILES IN MY LIBRARY), with the ability to unmerge/reset that setting. Or perhaps a "set target" setting I click for the first album I want to act as the "host" which makes a "merge to target" setting become visible, which will continue to display the target's album art once merged. (Or just display the album art of whichever one sorts first).
I know I can go in and get rid of the Disc folders, instead naming the files with disc (ie. 1-01, 1-02) but I'd like to not have to modify the files and instead set an internal rule for MusicBee to follow. I hope what I'm asking makes sense. It would be quite odd to combine only 2 out of 4 discs into the same Disc 1+2 folder, and then having separate Disc 3 and Disc 4 folders. Not to mention, I wouldn't be able to display separate album art during playback via Cover.jpg/Cover.png files for the discs I physically merge into the same folder.
I'm guessing this can be implemented by introducing a new type of flagging system that assigns a sequential value to each "merge" to keep track of merged discs/albums. So the first 2 discs I merge will be assigned the flag "1", for example, with the next unique merge being assigned "2".
Thank you!
I'm on 3.5.8056 P