This is posted in the non US forum but Canadian code follows US code on this.
The short answer is do not modify any fire alarm device. There is a manufactured product for what you want to do or it is prohibited to do it. All approved fire alarm devices are made and tested with the control panel. Pilot devices, relays, etc. are made according to applicable codes. If there is no alarm initiated relay for a signal circuit don't make one. You will wind up in court if there is any trouble. Believe me that even if your modification does not cause a problem it won't help you much at a coroner's inquest.
