Use AutoSync. You can toggle it Ctrl Shift Alt A / Cmd Opt Shift A or with a single click.
John
The Art of Retouching wrote:
AutoSync would have worked, except every other image usually needs a tiny tweak. That means I either need to click to turn it off, and click to turn it on again, or I need to click off the group, then on the single image. Once again, multiple clicks and/or keyboard actions.