Automation: Synchronize grouped cover positions

Hi, in my living room I have 3 covers controlled by a shelly each. I also have a group in HA to make them controllable by a single entity. While setting a specific position directly, everything works as expected. But when I use the UP/DOWN controls of the group entity, it naturally occurs that the 3 Shellys respond asynchronously. when I hit STOP, they might have different positions each.

Me first idea was to create an automation that sets the position of the group entity, 2 seconds after changing to state “OPEN” to the value of the “current_position” attribute of the group entity. This solution works so far! But there is one drawback: Now if I control just a single cover, the automation runs as well. I need a criteria to identity that the position change was initiated by the group and not by a specific member of it. Is this possible?

Here’s my current automation:

alias: "Wohnzimmer Rollos: Synchronisieren"
description: ""
triggers:
  - trigger: state
    entity_id:
      - cover.wohnzimmer_rollos
    to: open
    for:
      hours: 0
      minutes: 0
      seconds: 2
conditions: []
actions:
  - action: cover.set_cover_position
    metadata: {}
    data:
      position: "{{ state_attr('cover.wohnzimmer_rollos', 'current_position') | int }}"
    target:
      entity_id: cover.wohnzimmer_rollos
mode: single