The association group only provides a trigger from the sensor to turn on other devices (like the Heiman siren device) based on the smoke alarm to be triggered and has nothing to do with an option to turn on the siren itself.
Based on the documentation, I tried to trigger the siren with a custom flow card; but not successfull.
So based on this test, I don’t expect it to be possible.
Looking forward to the feedback / confirmation of Heiman
