This is a rehash of all the notes above, but I thought I'd list in one place the step-by-step instructions I used in case anyone else is in my shoes and still fairly new to all of this.
Using the tips in this thread all four double plugs I installed have paired very quickly and the communication flood stops.
- Get the Basic Z-Wave Tool as mentioned above.
- Start Z-wave include on Hubitat.
- Plug in a Zen25.
- When it pairs uncheck all security boxes. OK. Match Security Codes, ignore and click OK.
- In the Found Devices dialog enter a Device Label, Save Device.
- Go to Devices, select Parent Device.
- Change driver to the Basic Z-Wave Tool, Save Device.
- By this time the log is flooded with messages.
- Set parameterNumber:18, size:1, value:1. Click Set Parameter.
- Change the driver to Zooz Double Plug. Save device.
- Do Not Save Preferences. Thatโs what resets Param 18 to 4.
- The log flood stops.
- Update the child device names as needed.
Thanks to everyone who has done the troubleshooting.