Ok, lets call your switches 1, 2, 3, and 4.
Switch 1 is the main switch with the load attached. If not using smart bulbs, then this switch needs to NOT be in smart bulb mode, as this controls the actual on/off state.
Switches 2-4 can be in smart bulb mode, but it probably doesn’t matter.
EDIT:
Power from the panel should be feeding each switch, and only the light should be connected to the load on Switch 1
EDIT: I see you already have them in a group and functioning, so feel free to skip this part 
As far as binding goes, this is where I have less experience, as I haven’t bothered using 2 full fledged dimmers separately on the same lighting circuit. I think the best way of going about this is to add all 4 switches to a group and then bind Endpoint 2 of each of the switches individually to the group. If anyone else chimes in with a better/proven solution, I’d probably go with their solution.
-
If these are all VZM32s, you may end up experiencing issues with motion detection. Again, no experience with this setup, but this is based on other posts I have read through…
Again, I haven’t played around with multiple mmWave switches on the same circuit, so I’d hold off on taking my word for it and modifying anything til it proves to be a problem.
This is based on the default setting of Occupancy for the mmWave Control…
While the light might turn on at the detection of any of the switches, as soon as one of the switches turns off, it will likely turn off the light even if other switches still detect motion.
If you set it to Wasteful Occupancy, it will turn on automatically, but will need to be switched off. This should cause fewer issues as it won’t turn off when one of the switches stops detecting motion.
If you want it to both turn on when any of the switches detect motion and off only when ALL switches stop detecting motion, you will have to get a little creative with a Home Assistant automation. You could set all the switches to Disabled so the detection doesn’t trigger the switches at all, but I would probably suggest the Wasteful Occupancy as at least this turns the lights on for you with minimum delay. You can then monitor the Occupancy status of all the switches and when all are clear, you can use that as a trigger to turn off the lights.