wow you're getting some interesting replies. some thoughts from buffalo
ny: you may play with extra smoke detectors only in addition to the
dedicated approved systems and devices in your home, not interconnect
them to the minimum required devices in your building.
not permitted to connect other items to the inspected dedicated red
electrical smoke detector box circuit or its devices.
not permitted: altering a lifesaving safety device. you are creating a
hazard for yourself and others. especially if you die from smoke
inhalation, where only the stupidity will live on.