Maybe. They are only related if they share a common ancestor. There are lots of possibilities and some of them will be related and some will not.
Your daughters are great aunties if their nieces have kids. Your daughters kids are your grand children.
Cousins
They are your nieces and nephews and not your cousins
Your mother's sister's children are your 1st cousins.
Children of your siblings are nieces and nephews. Children of your spouse's siblings are still called nieces and nephews, but you are not related to them by blood.
Auntie is a loving term used by some instead of aunt. Aunties are aunts to their nieces and nephews. An aunt is the sister of a child's mother or father.
Your mother's nieces' children are your mother's grand nephews or grand nieces. They are your first cousins, once removed.
Second cousins.
Your borther-in-law's children are your nieces and nephews. You are their uncle or aunt, as is your spouse.
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.
You don't, simple as that. You could say cousins if it's that important, or "my aunt's nieces and nephews on the other side," but there isn't an actual term for that except your "uncle's wife's siblings children."
Your father's great nephew is the son of your father's niece or nephew. Your father's nieces and nephews are your first cousins. Their children are your father's great nieces and great nephews, and are your first cousins, once removed.