expression shapes duplicated with metatool: independence between score and parts

[Moran35]

Good morning everyone,
I am dealing with a large score for piano and orchestra of contemporary music. Lots of particular symbols, including tons of crescendos and diminuendos dal niente.
I created the crescendos as expression shapes and then defined a metatool for the original shape. So each time it is used, it creates a copy, which can be edited in the score without altering the original.
I also copied the same crescendo (same shape) on different staves using alt+up arrow/down arrow.
As far as the score is concerned everything works perfectly, but now I have come to a very painful fork in the road: PARTS!
Now, as you can imagine, changing the horizontal length of a crescendo in one part will affect all the other parts and also the score (some of these shapes being the same shape).
Is there any way in your opinion to make the crescendos independent? A way to duplicate them globally so that changing the length of a crescendo in one part leaves the others in the other parts (and in the score) unaffected?
I hope I have explained myself clearly, and thank you in advance for your answers!