How to interconnect Kidde smoke/co combo detectors Mod# KN-cope_IC with Edwards Heat detectors Mod# CR-135-2 using relay SM120X

How do you wire the above units so the smoke/co detectors will all ring when heat detectors are activated. The heat detectors are a two wire hook-up. Existing wiring to heat detectors is existing and in wall. Hard to change to 3-wire.