@tanguatlay,
tanguatlay wrote:I have replaced "man" with "father" in the second sentence. Does it make the relationship between the man and the child clearer?
No, it doesn't. The relationship is made absolutely clear in the first sentence. The only man who can watch
his child is the child's father. I suppose if you want to imply that the man is having fatherly feelings while watching his child, you might prefer to use 'father' instead of 'man'.