So, what's wrong with this photo? In this one, the child on the left (my son!) isn't quite cooperating. He's leaned back, not quite smiling or looking at the camera and his right hand was caught in motion. The other two children in the photo are fine. 

 

In this next shot, it's obvious what's wrong with it. Hey, it happens. This is why you take multiple shots! 

 

So onto Photoshop we go! Below you see the final product of a few minutes-worth of "magic". A little bit of Auto-Align Layers. A little bit of masking and brushing. And voila! This is what you get!