She is your father's or mother's mother.
Grandmother
He is your father's or mother's father
Grandfather
She is married to your father.
Mother/Mom
He is married to your mother.
Father/Dad
He is your sibling and he is a boy.
Brother
He is married to your sister.
Brother-in-law
She is married to your brother.
Sister-in-law
She is the daughter of your stepfather or stepmother.
Stepsister
He is the son of your stepfather or stepmother.
Stepbrother
He is the man you are going to marry.
Fiancé
She is your sibling and she is a girl.
Sister
He is your mother's or father's brother.
Uncle
He is your son or daughter's son.
Grandson
She is your mother's or father's sister.
Aunt
She is your son or daughter's daughter.
Granddaughter
He is your husband's or wife's father.
Father-in-law
She is your husband's or wife's mother.
Mother-in-law
He is your parent's sibling's child.
Cousin
He is the son of one of your parents but not both.
Half-brother
He is your daughter's husband.
Son-in-law
He is the son of your brother or sister.
Nephew
She is the daughter of your brother or sister.
Niece
She is your son's wife.
Daughter-in-law
She is the daughter of one of your parents but not both.
Half-sister
She is the woman you are going to marry.
Fiancée