@Adam_J_Gadway No need to code anything, what you’re trying to do is already built in to ST! I’m already doing exactly what you’re trying to do with with the First Alert Smoke/CO2 detectors and the Utilitech siren/strobe, here’s how:
In the Dashboard go to Damage and Danger, tap on the configuration gear in the upper right corner.
Go all the way down until you see Smoke and Carbon Monoxide, and tap on that.
Next, you’ll be asked to name the area to be monitored, and then tap on Next
In the next screen, tap on Alert Me and then the next screen will ask you what detector(s) to monitor. You can select as many as you want.
Select your notification preferences, as well as any cell numbers for SMS messages. Tap on Done
Now you’re back to beginning again, but this time tap on “Turn on lights for escape routes”
If the FotrezZ device is like the Utilitech device, it has “switch” capabilities, which is just like a light you can turn on/off. In the next screen, tap on Which Lights, and select your siren(s) and light(s), tap on Done. I turn on all my major lights in the house, plus the room light where the detector was tripped.
You’re back one screen again, so this time select the option to turn off the light/siren on All Clear. Tap on Done.

You’re back to the beginning again, but this time tap on Next in the upper right corner. In the next screen, tap Done. And then again in the next screen, tap Done.

That’s it! Now whenever the detector(s) go off so will any siren and light you have associated with it/them.
You should test to make sure all that works the way you expect since you have different devices than I do, but I know my set up works. My daughter recently severely overcooked a bag of popcorn in the microwave, and my sirens and lights all went off as planned.
Hopefully this helps you out.