[@RPforthatPR] We will definitely do that sometime later in the story. I have some hard challenges in store for our characters, so they will be sort of forced to collaborate in such way. For now, the idea is to start easy, and then develop new abilities, figuring out how to combine the two stones to work together, and so on.
Oh, Edgar wouldn't dare to take all five of them. If he was smart enough not to do that when he first got them, I'm sure he'll restrain from doing that now :D