How to add an emergency stop switch in a circuit?
Sounds like you need to begin with a conventional latching stop-start circuit: -



So, the circuit above will have another relay contact that feeds 24 volts to all your motors and, when the circuit is first powered, the relay will not be energized. To energize it press "start". A relay contact latches the start button contact.

To de-energize press "stop". Stop switches can be a series of emergency stop switches wired in series with the stop button above.