It is likely that you will need a custom Device Handler written to get both paddles to show up in ST. That can be done through the IDE and there are others in the community that like could do it easily. My programming skills are not that great.
However, If the device you are trying to control with the right switch is also a ZWave device you can do it with tweaker. From the Guide you posted, it appears that you will need to use tweaker and enter the device id for the other z wave device into association group 2. Then hit the configure button.
With this arrangement your TZ35D will communicate commands directly to the other device and not really use the controller. I do this with any permanently wired devices and control switches so these basic functions are not dependent on Smartthings and internet connection.
Tweaker of course is not a permanent Device Handler so switch it back to whatever Device handler you want to use.
I’m thinking this may be a good place to start looking for a DH. Eric has written many DHs and likely has one that would require minimal changes to work for both switches.