Flip objects to better match light sources in new background.
step 4 of 6
using the selection tool, cut out the "dad's" body, leaving out the arm that is holding the "child's" hand.
while object is selected press CTRL+SHIFT+J which will move the selection to a new separate layer.
CTRL+T on the new layer and right click in the transform box, select "flip vertical". Rotate and adjust to get body close to the removed arm.
use the clone brush on both object layers to smooth transition between the two layers and make a clean looking edit.
step 5 of 6
Duplicate the new object and use IMAGE > ADJUSTMENTS > BRIGHTNESS/CONTRAST and lower both the brightness and contrast completely. this is your new shadow layer. place this layer behind your object layer. press CTRL+T to transform the shadow. rotate, skew, and size the shadow as needed to fit the light source.
used the dodge and burn tools to adjust the lighting on the objects.
step 6 of 6
Add in extra details like the footprints... use the dodge and burn tools to create shadow and light in the sand to mimic a foot print.
add additional filtered layers to achieve your desired look and effect.