I have two Shelly Dimmer 2's that control one lamp each. When Dimmer #1 is set to some brightness, I would like it to set Dimmer #2 to the same brightness. Should be doable using an "Action URL" on "OUTPUT SWITCHED ON/OFF URL". But I can't find a way to encode the current brightness of Dimmer #1 into the URL to be sent to Dimmer #2. How can this be achieved?