Are you talking about tapping the tile of the accessory switch? That will send a command to the accessory switch, but it is up to the device to decide what to do with that.
I don’t know if there’s a way to configure it to forward that command to its associated switches, but I would expect not. That’s not the usual way Z-Wave would work – if you want to turn on those switches, you would send the commands straight to them, not through an accessory. The accessory is there as an extra physical affordance.
The associations are stored on the switch itself, not in SmartThings. The SmartThings way to turn on/off multiple switches is to use the SmartApp “The Big Switch.” When we add official support for these kind of devices, we probably won’t make them controllable like that, to make it clear they are working as a remote control, not an actuator.