On my Fadal, I use "mass modify" to adjust all my tools to the new offset. I do need to note down what the new offset is, then enter the number in a calculator with a known number to figure out the amount the difference to move everything.
Another way I do it when machining multiple parts in vises for different ops, just pic a point that won't change like the top of the vise or a 123 block on the table, and set all tools to that height, then just do the Z offsets for the different parts in my cad/cam.
I am sure there is better ways to do it... maybe I will try some one day.