dei 520t w/ multiple sirens

My alarm (Clifford Matrix 3) has been installed and running fine for almost 8 years now. It's an elaborate install incorporating two 530T automatic window modules, extra sirens wired to a relay, and a DEI 520T battery backup system. Haven't had any problems out of it. I recently retested all functions of the alarm system and discovered that the 520T backup battery is dead and needs to be replaced, which doesn't surprise me, as the battery is very old. I am going to replace the dead DEI .7AH battery with an aftermarket SLA battery of 3.3AH or higher. Here's my issue: I'm wanting to find a way to power all additional sirens when the alarm is tripped...BOTH when the vehicle battery is connected and when the vehicle battery is disconnected/cut and the alarm is running off of 520T backup battery. I have included a picture of my current wiring for the extra sirens, showing how I used the brown siren output wire to trigger a relay, and the orange GWA output to prevent the extra sirens from chirping on arm/disarm. This works fine for me when the alarm is triggered and running off of vehicle battery power. This wiring method, of course, does not power the extra sirens when the vehicle's battery is disconnected, however, because of the necessary outboard relay. http://s15.postimage.org/s4fnkfc5n/Alarm_Current_Setup.jpg I am not certain how to incorporate the siren relay into the 520T to make it power the extra sirens under both scenarios. (the vehicle battery connected, AND the vehicle battery disconnected) I have included a picture of an idea that I had to make this work and wanted to run it by the experts to see what you think: http://s10.postimage.org/4obb6og4p/Alarm_Future_Setup.jpg Would this work? If not, do you have any suggestions on how I could go about making this work? Any help on this matter would be greatly appreciated. Thank you!

i think you got it right.

your second pic seems exactly how i would  do it.

yuk

quiet rural missouri, near KC.

If your system moves you physically and not emotionally, you have wasted your money.