Pointing to a boy,Seema said,"He is the son of my grandfather's only child". How is the boy related to Seema?

Pointing to a photograph,Arun said,'She is the mother of my brother's son's wife's daughter.' How is Arun related to the lady?

$(i)$ In a family of six persons $A, B, C, D, E$ and $F$,there are two married couples.
$(ii)$ $D$ is the grandmother of $A$ and mother of $B$.
$(iii)$ $C$ is the wife of $B$ and mother of $F$.
$(iv)$ $F$ is the granddaughter of $E$.
Who among the following is one of the couples?

$A$ family consists of six members $P, Q, R, X, Y$ and $Z$. $Q$ is the son of $R$ but $R$ is not the mother of $Q$. $P$ and $R$ are a married couple. $Y$ is the brother of $R$. $X$ is the daughter of $P$. $Z$ is the brother of $P$.
How many female members are there in the family?

Pointing to the lady in the photograph,Mrinalini said,"Her son's father is the only son-in-law of my mother". How is Mrinalini related to the lady?

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 $B$. Who is the wife of $E$?