Hi, Bunny. Liked your pictures on Fork Handles. Here is a link that might be helpful, since there are early and late-flowering spiraeas.
I guess the problem is that you want to move them and it would be easier to cut them back first. Really, the worst that can happen is that you lose this year's flowers.
I've one of those wedding spray ones. I put it right at the back of the border so that when the main flowers of summer come out we can't the leaves but when it flowers there isn't much in front - well that's the theory.
Hope it stays within its patch