??? I assume you are refering to the 'Copy to Background' method? You would have to start from the rear since if you start from the front you would have those in the rear super imposed 'in front' of those in the front. And you would not be able to cast any shadows on each proceeding one at all unless you use a flat plane and then the shadows would tend to float in mid air. Using the method I described with mutiple planes you would catch some shadows but as ernyoka1 points out they will not be exact as if there were actual characters (or props of characters) there. You could get some shadows but they are cast off flat image planes.