I’m looking to do the same thing with associating 2 switches - one is the Cooper RF9540 and the other is the accessory switch along with the IQ 2 Plus.
I’m able to associate the “accessory” (secondary) switch to the main switch. But, unfortunately I haven’t found a way to associate the main switch with the accessory. It simply shows that no groups exist for any of the lights I have on my system. This has resulted in everything partially working - accessory switch will turn on the light, but it’s not notified when the light is turned off from the other switch, so sometimes it takes two taps to turn the light on.
Is there a trick to associate a recognized ‘light’ switch with an accessory switch?