Combining Nodes for Positioning

I have created a simple composite consisting of a background, a foreground, and a polygon mask, with the foreground node as the mask's source. When adjusting the position of the mask relative to the background, I would like the foreground to move with it.
So far, the only way I can find to do this is to create a saver which includes the foreground and its mask, and apply the saver as the top layer of the composite. Is there a straightforward way without going through the file system to lock the foreground node and its mask together, so that their relative position does not change?

you want to mask the foreground with the polygon and then move the masked element over the BG?

you can attach the mask directly into the loader of the foreground or my way would to combine the mask and the foreground with a MatteControl node ("combine alpha" and check "post multiply image").
the add a transform node and then use a merge to combine the FG and BG element.

now you can move the cutout FG with the transform over the BG