It’s a paid dlc expansion, so no way to make everyone have both. People with only the vanilla game won’t have it. However, it should be noted that the only thing that I’m aware of that’s tied to the actual dlc that can’t be accessed by other players is the building sets. The items and recipes are all accessible in the game’s admin panel. They can’t be crafted by a player without the siptah dlc, but they can be used by players and released by Funcom. We’re already seeing decor from siptah dropping in the new purge. If they could release eldarium as a farmable resource, along with the recipes associated with it, it would be ideal.