As i have read many times on various forums, adding coins for trading on bitshares is the responsibility of the devs of said coins, not dex's. Noone controls the dex, so there is no one on our side to do that. And if the devs wanted to add their coin, it is pretty easy if i unerstand correctly.
That's the thing we need to spread the word about, so people that don't go to the dex because their shitcoin isn't traded there, will ask the devs to add it