If she is your grandpa's step-niece, she would be your mom's step-cousin, and your second step-cousin.
justin bieber has 2 stepsisters from his dads side.
A cousin.
your second cousin- in law or by her name lol
your auntie.. your sisters father is your dad..your dads brother is your uncle..your uncles daughter is your cousin and your cousins mother is your auntie:)!
Half blood sister
your cousin.
Joh'Vonnie.
great great uncle
jokes
Erin but his real moms name is patty and his dads name is Jeremy his dogs name is Sammy and his stepbrothers name is Jaxon and his stepsisters name is Jazmyn
His name is Hideki.
My father was my brother and my sister was my mother