I want to purchase the digital deluxe edition through the steam store, but I already own the standard shadowkeep edition. How can I go about purchasing the deluxe edition without having to pay for the entirety of shadowkeep and season of the undying again? On the xbox store, items you already own are discounted once put in the cart, but on steam it appears this does not happen. So, what is the best way to upgrade to the deluxe edition without having to pay the full price for it?
There currently is no upgrade option offered on any of the platforms. The best you can do is to contact Steam and see if they would refund you Shadowkeep in exchange for purchasing Shadowkeep Digital Deluxe.