You have two options.
First, recognizing that the Z-Relay is just a Heatit Z-Water with more relay channels and higher current capability, you might try the Z-Water driver which was recently added to the factory drivers. Hopefully it will recognize the additional channels and I'm confident it will correctly see the sensors.
Second, use this generic driver described here:
https://community.hubitat.com/t/heatit-z-water-generic-composite-driver/62394
I had great success using it with the Z-Water before the factory provided support.
