You're Great Niece or grand-niece. You are her great-uncle or great-aunt as the case may be.
If I understand the question, she's your niece.
Your grand daughter.
Great Grand daughter.
Your sister's daughter is your niece, her granddaughter is your "great niece"... or you could just call her by name.
Your sister's daughter is your niece, her granddaughter is your "great niece"... or you could just call her by name.
She is your Great Neice.
Your uncle's daughter is your cousin
daughter...daughter in law.
You would call your daughter's son by his name ex: Hi Jack.
you can call him your nephew if you are mom's daughter's sibling or if you will be the mom you can call him your grandson.
Your brother's daughter would be your niece. So she would call you Aunt/Uncle
The daughter of your husband's brother is his (and your) niece. Her daughter is his (and your) great niece.