The two to be sisters clasp hands as if going to arm wrestle. Take the piece of thread in the empty hands one end each and together tie it around the clasped hands. Say the friendship vows bellow then remove the thread, cut it in half with some scissors or a knife (both holding the scissors or knife) and each take a piece of the thread. These must be kept on your alters or in your friendship boxes(See how to prepare a friendship box at the bottom).
With this thread we bind our souls as sisters souls are bound.
With this thread we make a promise to stand as sisters stand.
With this thread we shall both be reborn from the mother as sisters.
How To Prepare Friendship Boxes
Take two boxes that are the same. Place the your box in your right hand and your sister do the same. Pass the boxes round your hands three times anticlockwise then swap the boxes so you get your sisters box. Then mark the box with a symbol of yourself. Then swap the boxes again and mark the other box with a symbol of yourself. Swap the boxes again and place your box somewhere else. When any friendship spells the boxes should be present as a way of mixing your energies even when your sister is not present.