That's correct, that's how it will work.During homing cycle (and assuming, the cycle move toward the home switch everytime), the CNC will home at the center, perfect. But now that I have a home switch in the middle of my area, will this act as limit switch during actual milling ? As far as I understand yes.
So whenever the CNC is aligned with homing switch, the Grbl will goes to ALARM and stop. Right ?
How about eliminating the middle home switches and using the corners per usual, then after your G28 home cycle you move to a specific location with G0 then reset that to your zero point with with G90?
Alternatively, you could add (human controlled) enable switches to the (CNC controlled) homing switches, then after your home cycle you flip the enable switches to disconnect the home switches.