Stage Size Change to the center

I have just recently finished creating a Flash animation.
However, I’ve decided to change the background image to an image that is larger then the present Stage Size.
I can easily change the stage size but as it enlarges from the bottom right corner down, I will need to move all my elements and layers down in order to center it all in the stage.
How can I move all of these layers with their timing down together so everything still fits together properly?
Is there a “lock to” function that will move everything togetether?

Is is there any way that I can change the canvas size to the center or to buttom?