"I wish," said Jon, "that since I could change Sarah's personality to anything while Sarah has it, I can change it to anything while Mom has it, too--and it would still count as 'Sarah's personality'."
"You're confusing me..." said Zoe. "Wait... Sarah McMillan?"
"Yeah," said Jon. "It's her. Wishes can't be reversed--you have to find loopholes. I wished Mom would have Sarah's personality. I can't reverse that. So I told the stone that anything at all is Sarah's personality--now I can change Mom any way I want.
"So what's gonna happen to Mom?"
"Very simple. I wish that until the swap with Sarah swears off, Mom would..."