A player that doesn't buy the expansion will still be able to play with others that does purchase it as long as they're playing the original content. There is no need to have them added to the disc already. now you're just talking out of your ass. Let me give you an example, I've stopped buying CoD's dlcs/expansions. I can play with friends who've bought the dlc just fine, just as long as it's not on the new maps. So your explanation holds no water here but please try again. Let me add another example, GoW also released DLC, I am able to play with friends just fine even though they bought the dlc just as long as it wasn't the new maps.