nephew in-law??
granddaughter
Step-brothers
Great uncle / Great nephew
No because that would be your cousin
The relationship between them is similar to father and son.
Your grandson is the great-nephew of your brother.
Youre his son.
Yes, she did. She had the relationship of a mother that a mother has with her son. As most mothers do.
He is your Grandfather, and is your son's Great-Grandfather.
Your younger brother's wife's sister's daughter would be your son's cousin.
Your son's wife is your daughter-in-law. Her brother is your son's brother-in-law, but the English language has no word for a relationship between you and him. You are not considered to be related to him.
She would be your son's second cousin.