Your mother's sister's daughter is your first cousin. That cousin's father's brother's son is her cousin. There is no relationship between you and this cousin's cousin unless there is another family connection.
Your first cousin, once removed, could be either your first cousin's child or your parent's first cousin.
The child of your first cousin, once removed, is your first cousin, twice removed, if your first cousin once removed is the child of your first cousin. If your first cousin once removed in the first cousin of one of your parents, the child is your second cousin.
If your first cousin once removed is your parent's first cousin, then your first cousin once removed is your child's first cousin twice removed.If your first cousin once removed is the child of your first cousin, then your first cousin once removed is your child's second cousin.
Your parent's first cousin is your first cousin, once removed. Your parent's first cousin, once removed is your first cousin, twice removed. Your parent's second cousin is your second cousin, once removed. Your parent's second cousin, once removed is your second cousin, twice removed.
Your 1st cousin's child is your 1st cousin once removed. Your 2nd cousin's child is your 2nd cousin once removed. And so on...
Your father's first cousin, once removed, is your 2nd cousin. Your father's second cousin, once removed, is your third cousin.
You are one generation out of synch. That would make you first cousins once removed.
The son of your second cousin is your second cousin, once removed. You are also his second cousin, once removed.
Your first cousin's son is your first cousins once removed. Your second cousin's son is your second cousin, once removed. Your 10th cousin's son is your 10th cousin, once removed. The child of any kind of cousin is that kind of cousin, once removed.
Your first cousin's child is your first cousin's, once removed. Your second cousin's child is your second cousin, once removed. Your third cousin's child is your third cousin, once removed.
Your first cousin's child is your first cousin, once removed. Your second cousin's child is your second cousin, once removed. Your third cousin's child is your third cousin, once removed. Your relationship to the children of cousins who are once, twice, or more removed is more complex and depends on whether you or the removed cousin are in the older generation.
The daughter of your first cousin once removed is your first cousin twice removed, or your second cousin, depending on which generation your are in compared to your first cousin once removed.
There are two ways you can have a first cousin, once removed.If your first cousin, once removed, is the first cousin of one of your parents, then the daughter is your second cousin.If your first cousin, once removed, is the child of your first cousin, then the daughter is your first cousin, twice removed.