Hi @Wolfreq, sorry for the delayed reply.
You can tweak an existing DTH by making a copy for yourself to customize. For your siren, you’ll need to know the “clusters” and “attributes” the device uses, which Develco does publish. Those should be close to, and/or, matching the Zigbee spec found on zigbee.org’s site.
You can use an existing DTH for your device and watch your IDE’s Live Logs to see what the device sends to the hub, and if the DTH isn’t sending events (usually through code starting with “log.debug”), you can add those where needed to capture the raw data from the device. I typically look for the part of the code where data is “parsed” from the device and then I send that raw data to the hub where I can see it via live logging. It will contain the cluster and attribute info you need to start figuring things out.
It could be that the existing DTH’s you’ve tried almost work, but just need a little tweaking to send the right config parameters to set up the device properly, or to look for a different cluster/attribute. You’ll need to know/learn a little about the Zigbee spec and what clusters/attributes to look for, as well and be familiar working with code.