You and your mother's first cousin are first cousins, once removed, to each other.
Your mother's aunt's son is her first cousin and your first cousin, once removed.
Your mothers sisters Granddaughter is your second cousin
The relationship to you would be your cousin !
She is your third cousin.
2nd Cousin
Your mother's first cousin is YOUR first cousin, once removed. The child of your mother's first cousin is YOUR second cousin.
You are their aunt or aunt by marriage.
If it is your first cousin, they are your first cousin once removed.
Your first cousin's child is your first cousin once removed.
Your first cousin's granddaughter is your first cousin, twice removed.
yes
You mother's first cousin is your first cousin, once removed.