In a family, there are six members A, B, C, D, E and F. 

A and B are a married couple, A being the male member. D is the only son of C, who is the brother of A. E is the sister of D. B is the daughter-in-law of F, whose husband has died. How is E related to C ? 

Clearly, D's father is the brother of C's father and C's father is A's Uncle. So, D's father is also A's Uncle. Thus, D is A's cousin.

Father's father ---->Grandfather;  Grandfather's granddaughter -----> Sister; Sister's husband ---->Brother-in-law. So, Y is X's Brother-in-law.

Only son of woman's grandfather - woman's father;  Man's brother's father - Man's father 

So, man's father is woman's father i.e woman is the man's sister.

Clearly, the brother of woman's mother is the same as the brother of the father of boy's maternal uncle. So, the woman's mother's brother is the boy's maternal uncle's father. Thus the woman's mother's brother's son is boy's maternal uncle, i.e woman's mother's  brother's daughter is boy's mother.

Arjun's son's wife's daughter ---- Arjun's son's daughter; Mother of daughter of Arjun's son - wife of Arjun's son.

So, Arjun is the father-in-law of the lady. 

K is the father-in-law of H means H is the wife of the brother (say, J) of the daughter (say, L) of K and K is a male (brother or father of some person, say P) i.e H @ J $ L # K $ P or H @ J $ L # K & P.

The relations may be analysed as follows :

Mother's husband ---> father,  father's father-in-law --->grandfather,  grandfather's son ---> uncle; uncle's daughter ---> cousin.