Draco:
You were Neville's twin sister, but you weren't clumsy like your brother. Everyone said it was because you came out first and happened to be three minutes older than him
George:
Being a Malfoy wasn't easy, everyone judged you by your family even though you were nothing like them at all. Being Draco's older sister was brilliant, whenever he would bully someone you could catch him and give him punishment
Fred:
You were Harry's sister, unlike Harry you were sent to live with people you didn't know. You weren't related. You were a year older than him so when you first arrived at the school you were confronted by rumours about having a younger brother you'd never even met
Ron:
You were Hermione's sister, you were a year younger than her and she was always telling you stories about her time at Hogwarts, Ron always caught your attention in those stories
Neville:
You were Draco's younger sister, he constantly teased you for being the clumsy one in the family and when you came to hogwarts you struck up a friendship with Neville
Harry
You were Ron's twin sister, twins ran in the family a lot and Mrs' Weasley ended up having two sets of twins in her family