\\\\ Pipp had just left her own spa and doesn't want to ruin her mane and fur getting into the Crystal Brighthouse's new pool. Misty makes an off hoof comment that she maybe knows a spell that would turn her water proof. Pipp begs her to cast the spell on her, but Misty would tell her that she's only read the spell once and hasn't actually tested it out. That she would need her spell book to make sure she even casts it right. Pipp would continue to plead until Misty gave in and she nervously casts the spell.
Unfortunately for Pipp, the spell works too well and starts to transform her into rubber. Flailing around and screaming she falls into the pool, but thankfully just floats back up as a pool toy. Misty panics and runs for her spell book, telling her she'll be right back. \\ Zipp is really confused having woken up and heard both of her sisters screaming only to find a pool toy of Pipp casually floating in the water, with no pony else around.
When she flies down to check on it, she's surprised by how life like it is.
She wouldn't ever tell Pipp about it, but she's always hated any of her merch that tried to replicate her little sister. The colours were always slightly off, the mane would always be too short, or they would always try to slim down her sister's gorgeous chubby figure!
The nerve of some ponies to cheapen her lovely sister.
The more she stared, the more enamoured she became, blushing as she let her hoof start roam her faux sister's face. Forgetting for a moment why she had even gone outside, and not even checking if there was anyone else to see, she brought the toy in for a kiss. \\ Pipp was screaming, at least she wanted to. She could feel her sisters lips on her rounded muzzle, feel her sisters hoof caressing her neck, and hear the whispered wishes of her big sister. She had no idea Zipp had felt this way.
And now she couldn't do anything to stop her sisters hooves from roaming wherever they wanted. \\ Misty looking on in horror, having run back with her spell book, hearing all the naughty things Zipp is saying about both her and Pipp. And wondering if maybe, Zipp wouldn't mind finding a Misty shaped pool toy in her bed shortly afterword.