Cousins?
your brother's daughter is you niece
your not your daughter is by marriage you are not
Your aunt's daughter is your first cousin.
Your brother's daughter is your niece. Her daughter is your great niece.
If you are married to your daughter's mother, then her boy is your stepson. If you are not married, then he is no relation to you. Either way, he is your daughter's half brother.
your uncles daughter would be your cousin
Your daughter is your uncle's grand niece.
brother's daughter relation
Your grandniece's daughter is your great-grandniece.
3rd cousin I think:-)
cousins
Your daughter's husband is your son-in-law.