How do I bind two Blue switches in Z2M?

Switches General Discussion
7

I have two Blue switches controlling one light.
Blue 1 has line, load and neutral.
Blue 2 just has line and neutral, so it’s not physically connected to the light, and also no traveller to Blue 1.

Just hoping for the best, for Blue 1, in Z2M I selected "Bind, then added the following to new binding:

  1. Source Endpoint: 2
  2. Destination: Blue 2
  3. Destination Endpoint: 1
  4. Clusters: LevelCtrl, OnOff checked

For Blue2, I also went to Z2M->Bind and added

  1. Source Endpoint: 2
  2. Destination: Blue 1
  3. Destination Endpoint: 1
  4. Clusters: LevelCtrl, OnOff checked

I have no idea what source or destination endpoints do, but everything works this way. With LevelCtrl checked but OnOff unchecked, I could change the brightness of the lights with the dimming function, but couldn’t turn the lights on or off. Checking “OnOff” fixed this, quite obviously in hindsight.

I didn’t check Identify or manuSpecificInovelliVZM31SN, not sure what these do.

Edit: All of this is spelled out in the post linked from the video, here:
How To's | Setup Zigbee Binding - Home Assistant (Zigbee2MQTT). Looks like I stumbled on the right solution.