Yeah, currently only your primary controller is going to be able to negotiate with and update any secured items like locks. However, if you're willing to setup an "extra" z-wave node on your network you could use it as a sort of a status bit for communication between your two panels.
i.e. have a z-wave duplex or appliance module somewhere you don't use. On = system is armed, set a scene (when A+ has it) to lock all doors when on status is detected. Off = system disarmed, turn on lights in the house and turn down thermostats.