Traktor Z2: Map Filter Knob to work on decks C/D

figured I'd do a modifier (hold down settings button on mixer - acts as a secondary shift, i've done this for other stuff and it's worked for changing cue point/eq's/gains/etc) and set it up so I can rotate the Filter on channel one to change the Filter on deck C

I've got it working but I need to be able to have it turn on the filter when it's anywhere away from 12'clock on the knob and have it turn off when it's at 12'clock

I'm assuming modifiers would be my solution, anyone got any insight? I'm a bit new to modifiers