Hello !
I know it's been months since the last reply but I just wanted to let you know that I finally took to the time to setup both things (custom mirror command + a UI button to turn off updateWithHistory on selected). Both seem to work as expected, so, thanks again for the support !

The dynamic mirror was truly driving me nuts when arranging parts for lasercutting. In this context various elements have to be placed according to the available bed space - hence having various parts be linked/changing during Move operations was constantly getting in the way and potentially causing errors (thus bad parts) if unnoticed. This fixes it.