First take a picture of the sleigh with a bag of packages made
to scale....
Next take pictures of your family in positions to get the
effect you are after....
Put them in the sleigh....
Then create a background and give it some motion....
add the night sky....
Throw in the moon you shot through the telescope
after blurring it for effect....
and all that is left will be to add the deer and sleigh image
you created....
The rest is magic.... well, it's a little more complicated than that but you get the idea.