How to blend a segment of an image with another image
Move the child down slightly so the right foot is behind the shoulder.
Reduce their size almost 50%.
Blend only the outline of the child with the background, at most a few pixels.
The men appear to be standing straight while the child appears to be leaned forward slightly - rotate the top of the inserted image backwards ~5°.
Reduce the brightness of the child slightly.


Doing the above should result in a realistic result.