You have to go to a book store one preferably with a reference section, go to the dark arts, and search for witchcraft. Or go to your local library and ask to see the back room, or whatever they call it there with the 'secret' books. These will include sexual books, paranormal books, and witch craft, dark magic etc. Your library were you live may not have one of these, in that case, you will have to hope that your book store does. Now me, I live in a little old town where witchcraft books have been stored for over a hundred years, so I have them. Not that I'm into that stuff, but that is what you would have to look for. Then just find the spell, or chant that 'says' your going to switch bodies, and preform it just as it says. Seance, candles, etc Have fun in your older sister's body!