Yeah, this is really an annoying problem.

As far as database changes this isn't exactly hard to do. A few extra columns in the current tables plus up to two small tables would probably be enough to scrap whatever faulty system they're using right now to track what games relate to what. They could even remove the requirement of owning a game to be allowed to buy its soundtrack or artbook.

The REAL problem lies in the coding changes if their store code is a mess. If it is, I can see why they are skittish about touching it... but even if they are afraid of breaking stuff it must be done sooner or later. The longer it goes, the harder it will be to change.

You are not wrong that this feature would help solve the issue (and solve other issue while at it), but I still maintain that it doesn't exempt Gog from the responsibility of marking that owners of [game X] Deluxe Edition possess the base [game X] and [game X] Deluxe Edition upgrade, or vice-versa.

This has been a much-complained-about big issue since GOG started doing editions and bundles and whatnot. It makes it impossible to browse the catalog or sales without spending A TON of effort into making sure you're not re-buying something. So why bother even looking?

There are myriad ways to fix it. (Looks like at least 3 brought up in this thread.)

I opened a couple support tickets with GOG when I had owned Title and all of Title's DLCs that would have been included in the Deluxe Edition (which was only made available later, after the game got no more DLCs) to get the Deluxe Edition marked as owned, and they declined.

It's a hassle! And every new bundle (like a bunch of "new bundles!" recently done as headline news...) and game-with-editions is another crack in the paint, shingle fallen off, chip in the window blighting the neighborhood through obvious lack of upkeep.

It's really BLEEPing annoying that GOG's not doing any basic maintenance and improvement where it matters... things like that. Or why TF are the news items on the bottom of the front page? (And so short -- we often-enough get more than 3 "pages" of news posts within a day, and yet I've emailed a couple times for that to have a basic fix (change the pagination counter to 4 maybe).

Instead, they're wasting resources on Galaxy, and getting games with DRM (or adding it to games) and who can say what else they're actually doing... By most counts, it's not answering tickets, or communicating with developers, or testing games before release either.