"How about I become Sarah instead?"
"What?" replied Jon. "Karyn, why does either of us have to become Sarah?"
"Well, we don't," said Karyn. "But I wanted to try something." Karyn shimmered and turned into Sarah. Her hair went back to blonde. Her breasts didn't change at all--the shapeshifter wish had given her a way to alter them, but Sarah had them anyway. No change was needed!
On the other hand, Karyn was dressed in more expensive clothing and her face had certainly changed. She may have gained a half inch or so in height, too.
"Okay, you're Sarah," said Jon. "What were you going to try?"
"Well, we have three choices. First, people can know I'm Karyn. Second, people think I always looked like Sarah. Third, people don't change and they're surprised to see me as Sarah. Third..."
"Fourth," said Jon. "Four shall be the number of thy counting, and the number of thy counting shall be four."
"That's three."
"Not in my version."
"Okay, fourth. People think I'm the real Sarah. People... all people. Sarah, much as I hate to admit it, is a 'people'... so Sarah would think I'm the real Sarah, too!"
"But I didn't mean it that way," said Jon.
"But you said it that way," retorted Karyn. "I'm going to try it. Let's go get some food at the mall food court. I think I heard Sarah say she was going to the mall. I wonder how she's going to react to me?"