ActionScript 3.0 :: Unloading Jpeg With Unload() Or RemoveChild()

I'm working on a project that is like a jigsaw puzzle.  The use can select from a few different puzzles that have different piece arrangements.  Once the puzzle swf file is loaded, the user can select images from a gallery to place in the pieces to make a custom puzzle where the puzzle piece movie clip that was selected masks the image that was selected.
 
So the puzzle swf loads fine and I add it to the stage with:
 
addChild(puzzle);
 
The jpegs also load and get masked correctly.  When I add the jpeg image, I add it to the puzzle object and the addChild looks like this:
 
puzzle.addChild(imageJPEGLoader);
imageJPEGLoader.load(new URLRequest(imageJPEGName));
imageJPEGLoader.x = 0;
imageJPEGLoader.y = 0;

[Code].....

I think I'm obviously not understanding the parent/child relationship fully.  I thought if imageJPEGLoader was inside puzzle, that the dot syntax would get me to the object I needed.  Everything works fine in this file except for putting a new jpeg on a piece that already had a jpeg masked.