If his great grandmother and your grandmother are firstcousins, the you and he are third cousins, once removed.
You are second cousins, once removed, to each other.
If your great grandfather was the brother of your husband's grandmother, then you and your husband are second cousins, once removed.
Cousins
You and the granddaughter of your grandmother's brothers, and sisters, are first cousins.
Your grandmother's sister is your great aunt. Your great aunt's daughter is your first cousin, once removed.
Your grandmother's sisters are your Great Aunts.
Your grandmother's brother is your great uncle.
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Your grandmother's sister is your great aunt.
When a couple is married and the wife has nieces who are daughters of her brothers or sisters, those nieces are also the nieces of her husband. So your great grandmother's sister's husband could have great nieces who are related to you and also great nieces who are not related to you.Note that your great grandmother's sister is your great great aunt.The great nieces who are related to you are the grandchildren of the siblings of your great great aunt.Those could be your:parentauntfirst cousins, once removedsecond cousins, once removed
He is your second cousin once removed. His children are your third cousins.
Your grandmother's mother is your great grandmother and your son's great-great-grandmother.
Your grandmother's brother is your great uncle.
Your grandmother's sister is your great aunt. You are her great niece, if you are a girl, or her great nephew, if you are a boy.
Your her great great aunt!