Your first cousin's sister is also your first cousin; your second cousin's sister is your second cousin, etc.
The son of your first cousin is your first cousin, once removed; of your second cousin is your second cousin, once removed; etc.
They would be a first cousin once removed.
That is your 2nd cousin. I know that you're parent's cousins are your 2nd cousin for sure. And that is the same as your cousin's child. WOOH! confusing stuff!
They're second cousins.
First cousin once removed.
you are an aunt or uncle of the sun
First cousins twice removed.
You and your first cousin's son are first cousins, once removed.
your son and your brother's son will be cousins
your son and your brother's son will be cousins
your son and your brother's son will be cousins
second cousins to his cousin's children, you'd be third cousins
Your son's child and your nephew are second cousins.
Your granddaughter and your niece's son are second cousins.
Your son and your aunt's child are first cousins, so your son and your aunts grandson (the son of your aunt's child) are first cousins, once removed.
He would be your second cousin.
Cousine
First cousins
First cousins