[black_eagle]

Personally, I'd be quite happy with a manual method of creating sets, something similar to how the videodb does it.

Can't do that when the current advice is to use Picard to do the tagging and add MBIDs to everything. These releases do not exist as separate parts.  See McCartney above - there are not separate MBIDs for the separate disks.

Whereas manually saying "This one should be split up into separate discs based on DiscSubtitles" would seem possible and maybe a little simpler.  If the flag is KODI's to set, then it can allow different values for different handling.

There are some thoughts ticking in my head to try and work out a way to assist with this... I also have rusty C\C++ skills from the previous century but don't always have the time.  But I do want nice boxsets in KODI so part of me may be tempted to try and help out in some way.  Especially as I have spent the last two years making sense of the madness that is the MB website and their "unusual ways". 

Errr, I looked at the McCartney RAM collection, as referenced in the thread, but it does indeed have disc subtitles for each individual disc.  As does Queen - The Platinum Collection, The Joshua Tree - 30th Anni. Deluxe Set. Even Pink Floyd - A tree full of secrets (bootleg) has disc subtitles.  Alternatively, if you're into jazz, there is the 21 CD box set from The Art Ensemble of Chicago, also with a full set of disc subtitles.

After a very quick look around on MB, I think I have to revise my opinion and say that auto-splitting using the disc subtitle looks eminently feasible. Of course, there are bound to be exceptions, such as Dylan which distinctly says 'Deluxe Box Set' on the back of my case but has no disc subtitles in the tags from MB - perhaps this is because the actual discs inside are just disc one, disc two & disc three ? In spite of the packaging, I'm inclined to consider it an anthology rather than a box-set anyway.