I purchased the basic edition of the game last week. I would like to upgrade to the premium edition, but when I add it to my cart on Steam, it won't let me proceed with the purchase because it is detecting that I already own the game.

Isn't there a way to purchase an upgrade for a higher edition that removes the price of the base game which you already have? I swear I've seen that with other Steam games.

So, I don't know who needs to hear this, but if you want me to buy the premium edition, I literally cannot until something changes about the store page...