Your first cousin's grandchild is your first cousin, twice removed.
Your grandchild and your niece are first cousins, once removed.
The grandchildren would be the parents, aunts and uncles, and first cousins once removed, of the great grandchildren.
Her first great grandchild will be born next December.
You and your uncle's great grandchild are first cousin, twice removed.
You and your first cousin's grandson are first cousins, twice removed, to each other.
Your uncle's child is your first cousin. His grandchild is your first cousin, once removed. You are also that grandchild's first cousin, once removed.
The grandchild of your grandmother's first cousin is your third cousin. The grandchild of your grandmother's second cousin is your fourth cousin. The grandchild of your grandmother's third cousin is your fifth cousin.
Mackenzie
nickie
You and your uncle's child are first cousins to each other. You and your uncle's grandchild are first cousins, once removed, to each other.
Your child and your nephew are first cousins, so your grandchild and your nephew are first cousins once removed.