How to create volume change on sonos device as a trigger?

Hi everyone,

I have several Sonos devices in the living room. I often group these together. However, when I control the volume on a Sonos device on top of the device, it does not control the whole group, but only that specific Sonos.

I would like to get it do control the whole group with a flow that if I control the volume on one device, it changes it for the whole group.

I think this should be possible by starting a flow in Homey>Sonos the “IF” category with IF “volume changed”.

However, I have no idea how to use this variable. It shows a blue tag behind which is stated “e.g. 0.5”. However, I can’t enter anything or change anything there as this seems fixed. Therefore, I don’t seem to succeed to implement the volume changing on my sonos device as a trigger

So ideally I would like that if I turn the volume down on Sonos device 1, on Sonos device 2 it changes the same relative volume or comes up to the same volume percentage as Sonos device 1.

I know this is not a lot of information I’m giving, but could someone get me started on how to start a trigger by tapping the volume button on a Sonos device, and thus causing the volume to change?

I’ve been fooling around for nice hours, but I really have no idea how this trigger works/can work in the “IF” category.

Thanks a lot if someone wants to take the trouble to help me or get me started!