Start with some post-hypnotic stuff

Neo got to work.

"Any time Neo claps her hands, Velet will become her reflection in the mirror again."

"Any time Neo snaps her fingers, Coco will return to being her robot self again."

Then, under both pages.

"Whenever Neo repeats these actions while they are in their other forms, Velvet/Coco will go back to human and not remember anything which transpired."

Now she could have them act that way whenever she desired, and they wouldn't be any the wiser. Glynda's smarts were fun when they were on Neo's side.

Now to do something to Cinder. Something her boss wouldn't forget for a long time.