Professional :: Background Scrolling - Attach The Trees To The Background?

I have converted a large background image (much larger than the stage) into a Movie Clip.  I did this so I can make it scroll as the player traverses to the edge of the scene.This appears to make the player free to roam the entire background image.I have a tree symbol with a class attached to it that blocks player movement.Here is my problem:

When I drag and drop instances of the tree symbol onto the background, the trees are stationary and do not scroll with the background.I do not want to have to implement code to make the trees scroll when the background does.I was wondering if there was a way to simply attach the trees to the background so that if the background moves, the trees move with it and appear to be part of the background as if they were drawn into it.It is convenient for me to be able to drag and drop as many trees as i need to block certain routes on the background from the player.I tried writing code to make the trees move but it was only working for the very last tree that I added to the scene.