Three's company!

"Hey, Johnny boy," Sarah taunted, cupping Jon in her hand, "I'm not done with you yet. I've always wondered what it would be like to be different from everyone else, to have an advantage none of the other girls can match. I wish that Jon's creepy goth sister, Zoe, was standing right there," she pronounced, pointing at the floor. The stone flashed, and a very confused looking Zoe appeared, wearing one of her characteristic Goth outfits.
"What the fuck, how did I get here? What are you doing here, queen bitch? and why are you topless?"
"I wish you knew what I did to your brother and his friend," said Sarah.
"What the hell are you talking about, Mikey is just fi-" and she was cut off as she suddenly remembered Jon. An image of him and some girl, who her mind told her was "Karyn", transforming into breasts, appeared in her mind.
"The hell... how did you do that? Make something appear in my head? This is one fucked up dream..."
"I assure you, you're not dreaming. I used this wishing rock I stole from your brother to turn him and his loser friend into my breasts," explained Sarah.
Zoe began to remember memories of Jon... of her intense rivalry with him, and how she always wanted to get back at him for making fun of her goth style.
"Huh. Well, the little jerk deserved it. Any reason why you wished me here other than to gloat?"
"Actually, I hate you just as much as Jon, you little goth freak. I'm tired of your black outfits and mascara ruining my good mood. So, I figure I'll get rid of you, too."
Zoe looked in horror as Sarah prepared for her revenge.
"I wish that Zoe was my third, middle breast, and could communicate with both Jon and Karyn. I also wish that all of my clothes were designed to accommodate my three breasts comfortably."
From Sarah's chest, Jon watched on in shock as his sister underwent the same transformation as he did. Her black clothes became unwoven into a pile of thread and cloth, leaving her nude.
"You'll never get away with this you bitch!" was her last cry of defiance before the magic forced her to curl into a ball. The ripples of changes smoothed away the features of her body, as her butt cheeks fused together and her vagina closed up. Her arms and legs melted, losing their bones as they became the underside of her new breast-body. Her face was twisted in an expression of terror as it became flush with her body, losing its definition and becoming a nipple. Her old nose ring became a nipple piercing instead. As she shrunk down to breast size, Sarah walked over to her, smirking smugly.
"Oh, you will look just perfect with the others!" she pronounced, picking her up in her hand. Sarah used her free hand to slide Jon and Karyn to the side, leaving a flat space between them. She then pressed Zoe's back end firmly against her chest. Jon felt a warm presence next to him, and knew that his sister now shared his fate.