"Hold on, let me think," said Karyn.
She remembered everything, of course, since all the wishes in question were made by her. First of all way back was the blonde hair and breasts wish. Then there was the machine making her idolize Sarah. Then she wished to be Sarah's sister. Then the machine being used to make her disappear--but somehow she was still there.
But that seemed wrong, somehow. "I wish I knew what's going on."
The answer was that wishes are not reversible, but dream machines are. Sarah wished Karyn back. That wish reversed the effect of the dream machine--so she no longer idolized Sarah, and so she hadn't disappeared--but it couldn't reverse the effect of wishes--so she was still Sarah's sister, Jon was still Joy, and the other wishes were still in effect.
She wondered what, in this new reality, her relationship to Sarah was. Was she close to Sarah because of the dream machine (reversed) or because she was Sarah's sister (not reversed)? But it probably didn't matter--Jon, Alan, and Sarah all heard the wish and remembered them being close.
"I wish Sarah would let Joy and Alan go, then leave, while thinking it was her own idea. I wish she wouldn't remember these two wishes either.
Sarah, expecting her loyal sister, was suddenly puzzled as this betrayal, as she was forced by the wish to say "You two can move now." She didn't even have a chance to become outraged since immediately after that the wish made her enter the house and forget.
"What?" said Joy. "Are you helping us? I suspected it brought you back differently."
"I'm not sure if we can trust her," said Alan, who never knew Jon or Karyn in the original reality, and (like Joy) remembered only the bitchy Karyn anyway.
Karyn shook her head. "You can trust me. This is screwed up. I never had my memories changed by any of this, so I remember being Jon's friend. The machine made it so I wasn't, and the stone made it so that I was Sarah's sister and he didn't even remember that I was. The machine part is gone now. I'm still Sarah's sister but I don't think you're scum any more. I just don't know what we should do now."