Yeah, the fireball trick was how I knew there was something behind that wall. I didn't think about trying to remove the bushes. In earlier expansions you could count on yellow bushes being removable. Now they are everywhere.
I have talked to every child in the workshop several times. Am I supposed to do something else? All say they can make something for me except the one in the west side, who just says "We are all children of the fairy folk."