As they came to the store and entered the old man greeted them. They both replied almost in unison, "Oh good your here!"
Old Man: "What can I do for you girls?"
Amy: "Could you help us with this collar, I'm shrinking and Lina is growing exactly what I lose. What the hell is with this?"
Old man: "Did you not read the sign off the rack when you picked this item? Sorry I usually tell folks what each item does just in case, must have slipped my mind. Anyhow, that is an enchanted pet leash. Since you have the collar part you will become an creature of some sort but you can keep your personality and mind, it's up to whomever gets linked by holding the leash, it would be Lina I suppose. The creature to be chosen would affect both of your heights, bigger the creature the smaller the one in control would be, vice versa. Even if what you chose is too big it will still work, just that it would be a "dwarf" size compared to the real deal. The default until chosen is what you have now, the one to be a pet shrinks and transfers size. Once the transformation is complete the leash and collar can be removed, at that point I can help you two reverse the changes. You should make a choice soon because I've had people say others have shrink out of existence from indecision and there really isn't much I can do then."
Lina: "Er exactly how do I choose?"
Old man: "Oh that's simple, just say: I commend, then your friends name, to become blank. The blank being the description of the change that is to occur, be careful not to make it too unspecific otherwise she might loose her mind, personality, or both."
Lina: "Ok Amy, looks like there is no way around it, what would you want?"