MainStage gives you a few options for dealing with how the MIDI controller (nanoKontrol2 in this case) acts during patch changes (so that you can avoid any large control jumps). You can check out these options by going to MainStage 3 > Preferences > General You will want to specifically look at the options under “Respond to Hardware Move"
We recommend that you use the “Jump” setting, this is so that the fader/knob max-min range isn't limited (due to where it is at in relation to where it is at on the next patch). If there is something you know you will need to move during a song, you can just give the fader/knob a little wiggle before playing.
If you don’t like this method, there are two options:
A. You could buy a motorized fader MIDI controller (this will let you set up the controller’s faders to physically move to correspond with the MainStage controls (as long as it supports MIDI IN)
B. You can send every channel strip to a different bus, and because busses are Concert level, you could adjust them with your nanoKontrol2 fader and the fader/volume setting would stay the say, even on patch change. This is a bit tedious though and can be a lot more work if you are wanting to set up your concert or new patches this way.
Unfortunately, you would need to do either one of those things regardless of what MainStage concert you use, because MainStage is not built to have a default setting that accomplishes this functionality.
We have learned to look at patch changes as giving you the ability to have presets where all of the faders are automatically setup just how you want them. This way, you don’t jump to a patch and have the piano channel strip volume down, or the pad too loud- etc., It really saves you from needing to set all faders and knobs prior to playing a song. You can see it as one of MainStage’s greatest strengths where you don't have to move controls a lot in a live setting.