Explanation:

- P is the father-in-law of U. This implies that P's child is married to U.

- U is the mother of F and the only child of X. Thus, X is U's parent.

- J is the husband of X, making J the father of U.

- M is the brother of F, indicating that M and F are siblings.

- F is the son of W. W is then the mother of F and the wife of U.

- R is the mother of W, so R is F's maternal grandmother.

Based on these analyses:

- J, being the father of U and grandfather of F (since F is the son of U), makes F the grandson of J.

- Grandson