You not related to that person.
She would be the same relation to you as she is to him.
Real sister, half sister, or step sister
She would be his step sister.
Through marriage your step - sister's daughter is your step-niece!
Her step/half sister
step brother and sister
Half sister is when they have a different father. If your mom got remarried and had a kid with your step dad, it'd be your half sister(if it's a girl, of course.). A step sister is when your mom or dad gets remarried and their spouse already had a child and you have to relation to him/her.
Your grandfather's sister is your great aunt.
Yes, that child would be considered your half-brother or half-sister, not a step-sibling. A step-sibling is typically defined as the child of a stepparent, where there is no biological relation. Since you share one biological parent with that child, they are classified as a half-sibling.
Yes, you would be the step-nan (or step-grandmother) to your granddaughter's step-brothers.
David and Kelly on 90210 are step brother and sister.
She would be your step-sister