X is the father of Y, and Y is the mother of Z, making X the grandfather of Z.

Z is the daughter of X as Y (Z's mother) is married to X.

X is the sister of Y, and since Y is the brother of Z, X is also the sister of Z.

Y is the sister of Z, making her A's daughter as well.

A is the father of B, and B is the mother of D, making A the grandfather of D.

M is the daughter of N, making N the grandmother of K.

M is the brother of N, and since N is the father of O, M is the uncle of O.

R is the daughter of S, making S the grandmother of P.

S is the sister-in-law of P as she is the sister of P's husband, R.

X is the grandson of Z because Y (the mother) is the daughter of Z.