I did it again ... for you Photoshop Elements 6.0 people - this is the GREATEST tool. I can never get a group of children to look at the camera at the same time, and now I don't have to. I took about 6 photos of this group and managed to find 2 good ones - but both had one person not looking. I selected the 2 photos that I thought I'd use (it works best if they are the same shot (i.e. same distance and little movement between pics). I clicked "GUIDED EDIT". I chose "faces" at the bottom ... and on the left picture, coloured in the person I wanted to add to the right picture. It sounds confusing - but fiddle with it. It's SUPER easy to try ... I know I've done this before - but I haven't done it with a group shot - SO PUMPED.
Here's the first pic I chose ...