By the time the parents come home with lil sis in tow, the ex-boy is wholly incontinent by night, refuses to wear 'his' old clothes, and is uncomfy without the plug in place…
Big sis getting tasked with fixing her mind-breaking, though her idea of fixing may not be what the parents want. Only furthering the descent until the once middle bro is the new little sis, complete with a proper cookie in the front courtesy of a shady surgeon during spring break.