I believe that switch is for fwd/off/rev, or high/off/low. You would want a switch with 9 terminals, 3 input, and 3 outputs for each motor.
Keep in mind, you do not want to use the factory on/off switches with a VFD, unless you have them wired to the VFD, to power the VFD. Trying to get all that wired up, and also be able to switch which motor they are using, will be a sanity check. Unless you are going to use the controls on the front of the VFD each time.
I seriously gave the same thing a lot of thought. I have a four head Fosdick drill press. Basically a humungus stand, and four individual identical drill presses. After a lot of thought, I went with 4 VFDs. It would not have been that hard, as all the motors are the same, and the controls at the front, But the switching, and possibility of the switches being turned, made the decision for me. Also, afraid of a accident by turning the VFD on, and it is niot switched to the drill press I am thinking it is.