I see four generations here: 4. you (grandmother's daughter's son). 3. your mother (grandmother's daughter). 2. your grandmother. 1. your great grandmother and great uncle (grandmother's mother and her brother). Your great uncle's (gen 1) natural-born kids are your grandmother's (gen 2) first cousins and your mother's (gen 3) first cousins once removed.
Your grandmother's brother is your parent's uncle. The uncle's child would be your parents first cousin. You would be second cousins.
Your grandmother's brother is your great uncle. Your great uncle's grandchildren are your second cousins.
your brother's daughter is you niece
brother's daughter relation
Your brother's daughter is your niece. Her daughter is your great niece.
Your aunt is either your parent's sister or the wife of your parent's brother. If she is your parent's sister, her husband, his sister and her daughter are not related to you. If your aunt is the wife of your parent's brother, then her husband's sister is your mother (and her daughter is you or your sister) or she is another of your aunts (and her daughter is your first cousin).
Yes, the brother's children would be nieces and nephews of the great-great-grandmother; aka his sister. Great-great grandmother's daughter would be a 1st cousin to the brother's children. She would be the niece of the brother. The great-great grandmother's daughter's daughter would be a 1st cousin once removed in relation to the nieces & nephews. (# of removed depends on generations separating the relatives.) She would be a grand-niece to the brother. The great-great-grandmother's daughter's daughter's son would be a 1st cousin twice removed to the brother's children (nieces and nephews of the gggma) and a great-grand nephew to the brother. The person at this link does an excellent job of explaining this. http://www.ourancestry.com/cousins.html
You are not related as you do not share a common ancestor.
Quite possibly not at all as your cousins' grandmother need be no blood relation to you at all on one side of their family. At the other extreme it could be you or your brother, or you could be a first cousin. Plus lots of other possibilities - for instance, your brother could have married your cousin's grandmother's daughter, making the person your nephew.
It could be your father. Your niece's daughter's grandmother is your aunt. Her brother's son's father is either your father or your uncle.
Your great grandmother's brother is your great great uncle. Your parent and the grandson of your great great uncle are Second Cousins. Therefore you and the grandson of your great great uncle are Second Cousins, once removed.
No, Brother-Sister relation