thanks for the feedback and sorry for the vague wording. I want to change the formula of a dependent variable (e.g. var1=var2*var3 --> var1=var4/var5).
Seems like I have to do it manually, which fortunately is not too much effort in my case. For bigger tasks, maybe I could use SQL but I'm not that confident with this yet.
Would still be great if in the future there was a way to do it via the parameters tab at the product system level. Anyways, my case is probably too specific to be worth the development effort though.