Associating manually created devices with a plugin

I manually created a few Sonos devices a few years ago. Now the Sonos plugin is in the store.

For a new Sonos Device I purchased recently it has a “plugin” field with value of 4226 (the Sonos plugin) and it shows up as a device under the Sonos Plugin in apps.

I have 4 other Sonos devices. I’d like to add this “plugin” field to them on the device advanced “params” tab.

Any way to do this?

At the bottom of the Advanced tab, there should be a New Variable, New Value and Add button.

This is UI7. there is a new service tab but it also requires a service name.