They are ...
CHILDREN or BROTHER and SISTER
Who is he?
He is a GRANDPA or GRANDFATHER.
They are ... (in one word).
PARENTS
Who are they?
They are a FAMILY.
Who is she?
She is a MUM or MOTHER.
Who is he?
He is a DAD.
She is his little...
SISTER
The sister of your mum or your dad is your...
AUNT
MUM and DAD are your...
PARENTS
Who are they?
They are GRANDPARENTS.
He is her...
BROTHER
The brother of your mum or your dad is your...
UNCLE
Who is she?
She is a GRANDMA or GRANDMOTHER.