That would work without a problem, i think the question was more directed to you, if you allow it. Because the joiners for the DLC will get the Deluxe Edition content and not the base game .., which they already own.

So it could be seen as unfair, because people without owning the base game will get way more value of it.

But if you are fine with DLC joining, thats fine :) - many people are somewhat collectors here ^^

Thanks for the GA btw.!