1. Define a new function e.g. "Butterfly" and assign the stick you will control it with e.g. P4.
2. Now you can apply a function curve to this function, in this example I have no movement at top of stick = no butterfly applied even if stick isnt all the way forward.
3. Set up Butterfly in normal menu, when selecting Control press + and now you get the new list of available inputs
WIth this update the "Functions" really are at the top level of control, fine tuning via Function curves either global or flight phase specific.
For me it has meant that I could drop several free mixers and a LUA script, making for a simpler setup of otherwise complex models.