Resize stage from the center

Hi

I've been working to a 960px width and created my elements and animated them, but could now do with adjusting the width to 1200px. Is there a way to resize the stage from the center position? As when I currently change it I have to move the elements back to the center line, messing up my animations.

Or is there an easier way of resizing, then moving all the elements to the right along with the animations?

Thanks