Hey Johan
I think I get the idea but two parameters changing each other (with an added offset) might not be easy to get exactly right. I’m not sure if something like this would play nicely with automation and presets and other details.
On the other hand macro parameters (as seen in the emergence modulation system) would allow changing multiple parameters with one knob in a very flexible way (any number of parameters changed by different amounts if needed). Is this close to what you are asking for? let me know what you think