You open the menu and find awareness toggles. Clicking Mary you switch her from "unaware" to "aware of new changes". Best not to confuse her with what's already been done you decide.
"Here I set it so you will notice changes now. Don't do anything too crazy."
You had the phone over to her and hope you aren't making a mistake. She takes the phone and examines it wondering if her brother is just messing with her.
"The twins stand in the kitchen."
"The twins stand in the mall."
You suddenly find the kitchen replaced with the mall food court. And look to see Mary wide eyed."
"Wow it really works! What should we do now?"