Step-great-granddaughter
Your brother's granddaughter is your great niece and you are her great uncle if you are a man, or her great aunt if you are a woman..
Your sister's granddaughter is your great niece and you are her great aunt (if you are a woman) or great uncle (if you are a man).
Your great uncle's granddaughter is your second cousin.
Your aunt is great great aunt to your son's daughter (your granddaughter). Your granddaughter is your aunt's great great niece.
If you are a woman, you are your great grandmother's great granddaughter so your son is the son of her great granddaughter. But there are other possible relationships to other of her great granddaughters.The great granddaughter could be your sister. Then your son is her nephew and she is his aunt.The great granddaughter could be your first cousin. Then she and your son are first cousins, once removed.The great granddaughter could be your second cousin. Then she and your son are second cousins, once removed.
You and the granddaughter of your great grandmother's first cousin are third cousins, once removed.
Your uncle's great granddaughter is your first cousin, twice removed.
If you are a girl, your are your great aunt's cousin's granddaughter. If you are a boy, your sister is. Your great aunt also has first cousins from whom you are not descended. For those first cousins, the granddaughter is your first cousin, twice removed, or your first cousin, or your second cousin once removed, or your third cousin.
June 30, 2006
If you are a girl, your are your great aunt's cousin's granddaughter. If you are a boy, your sister is. Your great aunt also has first cousins from whom you are not descended. For those first cousins, the granddaughter is your first cousin, twice removed, or your first cousin, or your second cousin once removed, or your third cousin.
You granddaughter is a great great niece of your aunt. Your aunt is your granddaughter's great great aunt.
Your grand-niece.
The great great grand daughter would be my cousin sister.
Example: Great-great-great Granddaughter Katie
Your granddaughter is your sister's great niece. Your sister is your granddaughter's great aunt.
Your sister is her great grandaunt.