To save DSP on the FM3, I recommend setting up pedal 1 as a global volume pedal, detailed in the manual page 11.
Setup > I/O > Pedal > Pedal 2 Setup: 2 Switches (Tip + Ring) - This adds two additional footswitches with a TRS footswitch, just like on the HX Stomp. I have two recommended TRS footswitches at different price points linked in the HX Stomp section of my gear page.
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