A said "that boy is the grandson of my mother's husband. I have no brother or sister." How is the boy related to A?

If A is the husband of B, C is the brother of B, and D is the son of C, then how is D related to A?

While introducing a man to her husband, a woman said his brother's father is the only son of my grandfather. How is the woman related to this man?

If A is the mother of B, C is the father of D, B is the sister of D, and E is the son of C, then how is A related to E?

If P is the mother of Q, R is the father of S, Q is the sister of S, and T is the son of R, then how is T related to Q?

If A is the sister of B, B is the brother of C, and C is the father of D, then how is A related to D?