Your grandmother's sister's children are your first cousins, once removed.
Your grandmother's sister is your great-aunt.
Yes, your great grandmother's sister is your great-great aunt. Your great aunt is your grandmother's sister.
That depends, if you are referring to grandmothers as in a group or multiple grandmothers no, if you implying it belongs to a singular grandomother it would be "grandmother's" and finally if its something possessed by multiple grandmothers it would be "grandmothers'"
Marrie Carrie was named after her grandmother and her grandmothers sister (great aunt)
Yes, it would be correct to say that your family has a history of healthcare professionals. Your grandfather was a Pediatrician, your father is a Cardiologist, and both grandmothers along with one great grandmother were Nurses.
Your sister's son is her grandson and your great nephew. Some use the term "grand nephew."
Your sister's son is her grandson and your great nephew. Some use the term "grand nephew."
If she's not your mother, that would make her your Aunt.
Grandmothers for Peace was created in 1982.
I don’t know
First cousins once removed. They would be your parent's cousin.
The plural possessive is grandmothers'.