The grand daughter of your great great great grandfather could be your great grandmother, your great great aunt, your first cousin thrice removed, or your second cousin twice removed.
Your sister is her great grandaunt.
Your brothers great granddaughter is your great great niece.
Your granddaughter is your sister's great niece. Your sister is your granddaughter's great aunt.
Your sister is the great-aunt (also written great aunt) of your granddaughter.
She would be your great grandmother
Your uncle's great granddaughter is your first cousin, twice removed.
Your niece's granddaughter is your great great niece. You are her great great aunt (if you are a woman) or her great great uncle (if you are a man).
great aunt
Your great aunt is the sister of your great grandparent. Her granddaughter is your second cousin and her great granddaughter is your second cousin, once removed.
yes
He would be your great-great uncle.
Your aunt is great great aunt to your son's daughter (your granddaughter). Your granddaughter is your aunt's great great niece.