I just found it to happen way to fast and so unfulfilled. There should have been more to happen in that castle than just their "hide and seek". I do agree about that they most likely have released Pandora box because of their actions and while I'm not totally sure about how pure the mothers actions are, I doubt it will go as planed.
Instead of working with the sousui I would have to go with the conclusion that all she wants is pure deconstruction and this is a way to probably destroy a great portion of the world.