I'm going to make my game free, but some of the content in my game is going to be moved to DLCs.  The issue is that people that already own the game won't have those new DLCs.  This is easy to handle on Steam, but I'm not sure how to do it here on itch.

I would be happy to give the DLC keys to anybody that asks, because I can verify their purchase e-mail address, but I don't want everybody to have to request keys for something they already bought.

One option is to keep the game paid here on itch.. but I don't really want to do that.

So maybe there is a way to handle this situation that I just haven't thought of yet.

You can make the base game free and then set a minimum purchase price on the DLC content. Any existing owners will have access to a download page that will grant them access to paid content. (This is assuming the DLC price is below their original purchase price)

But if somebody got the game via a download link, then I guess they wouldn't have "spent" that amount, and so they wouldn't get the DLC content?  That doesn't work for me.  So I'm still actually not sure how to handle this situation.  Perhaps I'll keep the game here on itch the same as it is.  But I'd really like to offer the same free content here as I do on Steam, but there just doesn't seem to be a fair way to do it.  For me it is all about fairness for the consumer, and I'm not happy that I'm not finding a solution.