Pointing to a photograph,a man tells his friend,"She is the daughter of the only son of my father's wife." How is the girl in the photograph related to the man?

All the six members of a family $A, B, C, D, E$ and $F$ are travelling together. $B$ is the son of $C$ but $C$ is not the mother of $B$. $A$ and $C$ are a married couple. $E$ is the brother of $C$. $D$ is the daughter of $A$. $F$ is the brother of $B$. How many male members are there in the family?

To find out the answer to the above question,which of the statements can be dispensed with?

$A + B$ means $A$ is the father of $B$; $A - B$ means $A$ is the wife of $B$; $A \times B$ means $A$ is the brother of $B$; $A \div B$ means $A$ is the daughter of $B$. If $P - R + Q$,which of the following statements is true?

$A$ is the son of $B$. $C$,$B$'s sister,has a son $D$ and a daughter $E$. $F$ is the maternal uncle of $D$. How is $A$ related to $D$?

Pointing to a lady,a girl said,"She is the daughter-in-law of the grandmother of my father's only son." How is the lady related to the girl?