First, each room must have overhead access to the other rooms to be treated. See our FAQ related to ceiling types for additional info. Second, if the other rooms are separated by a firewall, then you will need to consult with your local government to determine if, or how, you may connect via venting. If there are no physical, legal or safety impediments, you simply “T” or “Y” in additional flexible air ducts and run them from the main UVC chamber to each room.  Each room will need an intake and an exhaust duct/vent. There is a limit to how much you can split your ducts and which diameter ducts and fans to use. We may be able to provide guidance or you can consult with a licensed HVAC technician in your area.