quarter sister
The half sister of my half sister or half brother.
Amy and Randy had Josie. Randy and Patty had Vanna. Patty and Bob had Andy.
Vanna is Josie's half sister.
Vanna is Andy's half sister.
Josie is Andy's quarter sister.
Andy is Josie's quarter brother.
Vanna is Josie's half sister.
Vanna is Andy's half sister.
Josie is Andy's quarter sister.
Andy is Josie's quarter brother.
three-quarter-sister
Daughter of a person's father with that same person's maternal aunt or daughter of a person's mother with that same person's paternal uncle.
My three-quarter-sister is a good person.