Yes, you would be the step-nan (or step-grandmother) to your granddaughter's step-brothers.
Nephews and nieces
Your brothers great granddaughter is your great great niece.
your niece
Your uncle's granddaughter and your child are second cousins.
Your daughter and your brother's child are first cousins to each other.Your daughter and your brother's granddaughter are first cousins, once removed, to each other. The "once removed" refers to the fact that they are separated by one generation if you count from their common ancestor, your parents.
You granddaughter is a great great niece of your aunt. Your aunt is your granddaughter's great great aunt.
Great neice
Your granddaughter and grand niece are second cousins to each other.
Your great nephew and your granddaughter are second cousins to each other.
There is 2 answers your mothers brothers children or your dads sister;"s children
No. The sister is a relation, and her husband is an in-law. The husband's brother is no biological relation either. Therefore, the great granddaughter of the husband's brother is not a relation.