hi rick,
You are doing perfectly right. The relative position of those smart shapes should be maintained even between the breakpoints for such setting. Please check if the smart shape position properties(left, top) are in %unit or Pixel unit.
If the units are in % they(objects) always move wrt to slide width and height.also re positioning the objects at breakpoints also not needed.
Let me know if this solves your issue. Otherwise please post a snapshot of your position property panel settings.(at three break points) or send me the cptx file through dropbox.
Thanks
Devraj