How to connect morph targets to themselves?

Hello. If I want to get something similar to drivers from Blender, I mean to connect values of morph targets to themselves, how can I do that? I just want to change one of the morphs and it should cause the changing of another one with some kind of pattern. Here’s example from Blender:


Every line is a value changing pattern. Maybe curves can help me with it? Or something else made special for that case?