Your son and your nephew are first cousins to each other.
Their daughters are second cousins to each other.
If I were you, I would break up with him. Not only because he doesn't like your daughter, but if you think about it; How would that effect your daughters life, and her relationship with you.
It Depends. Not every daughter father relationship is the same. There are daughters who hate their father. And their are some who love them because there he onlyones there for them. Everybody's different.
They would be great nieces or great nephews.
Technically there is no relationship. When introducing her, you would refer to her as My daughter's mother-in-law.
Your brother's children would be your nieces and nephews.
Daughter's means belonging to your one daughter. (possessive singular) Daughters means you're talking about more than one daughter. (plural) If you want to show something belongs to more than one daughter, you use daughters'. (possessive plural)
There would be no relationship as you do not share a common ancestor. If your brother-in-law is married to your sister, then her daughter is your niece, her husband would be referred to as your niece's husband.
A cousin, in all those difficult cases they are your cousins
She would be your Great/ Grand Niece. Seeing as you are her Great Aunt or Uncle.
Every father daughter relationship is different. Probably most fathers would want their daughters to know that they deserve to be treated well, and that they should treat others well. They would want them to know their self worth.
Either they are second cousins or technically not related at all. Your cousin's niece would be one of her siblings' children, in which case it would one of your cousin's daughters, or her spouses' niece, in which case there is no blood relationship, but most families would refer to them as a cousin.
I think it would be your daughters 2nd cousin. (: