Your grandmother's first cousin is your first cousin, twice removed.
The children of her first cousin are your first cousins, once removed.
Your grandmother's sister's children are your first cousins, once removed.
If you and someone else have grandmothers who were First Cousins, the parents of those grandmothers were siblings and you and someone else have great-great-grandparents in common. Therefore you and someone else are Third Cousins.
you are second cousins.
If your great great grandmothers were sisters, your common ancestors are your great great great grandparents. That makes you 4th cousins.
If you are referring to YOUR grandmother and grandfather then your children are their great grandchildren. If you are referring to your parents, then your children are their grandchildren. The primary kinship dominates.
third cousins
You are third cousins.
Your mothers grandmothers children are each others siblings.
First, some of your cousins are not related to your grandmother at all. That is, your father's mother is not related to the cousins you have who are the children of your mother'ssiblings.On the same side of the family, your first cousins are your grandmother's other grandchildren. Your second cousins are your grandmother's great nieces and great nephews. Your third cousins are your grandmother's first cousins, twice removed, your fourth cousins are your grandmothers second cousins, twice removed, etc., etc.
Sisters, mother, aunts, grandmothers, nieces, cousins, etc.
It would technically be considered your half- cousin since you do have the same grandmother but a different grandfather.
First cousins once removed. They would be your parent's cousin.