Select multiple entities to link their on/off state. If any selected entity is turned on or off, the other selected entities will be sent a matching on or off command.

link_multiple_devices.yaml

blueprint:
  name: Link On/Off State of Multiple Devices
  description: "## Link On/Off State of Multiple Devices v1.0.3

    Select multiple entities to link their on/off state. If any selected
    entity is turned on or off, the other selected entities will be sent
    a matching on or off command.


    You can select any entity, but only entities supported by the
    `homeassistant.turn_on` or `homeassistant.turn_off` service calls
    will work.

    ### Requirements

    * All selected entities MUST suport `homeassistant.turn_on` and
      `homeassistant.turn_off` or errors will be logged and the blueprint
      will not work.

    * Requires Home Assistant 2022.5.0 or newer.

    ### Credits

    * [@adchevrier](https://community.home-assistant.io/u/adchevrier) for the
      [initial blueprint](https://community.home-assistant.io/t/synchronize-the-on-off-state-of-2-entities/259010)

    * [@hebus](https://community.home-assistant.io/u/hebus) for
      [this fantastic template](https://community.home-assistant.io/t/synchronize-the-on-off-state-of-2-entities/259010/38)"
  domain: automation
  homeassistant:
    min_version: 2022.5.0
  input:
    linked_entities:
      name: Entities to link
      selector:
        entity:
          multiple: true

mode: restart
max_exceeded: silent

variables:
  linked_entities: !input "linked_entities"

triggers:
  - trigger: state
    entity_id: !input "linked_entities"

condition:
  - condition: template
    value_template: >
      {{
        trigger.to_state.state != trigger.from_state.state
      }}
  - condition: template
    value_template: >
      {{
        (trigger.to_state.state == "on") or
        (trigger.to_state.state == "off")
      }}
  - condition: template
    value_template: >
      {{
        trigger.to_state.context.parent_id is none or (
          trigger.to_state.context.id != this.context.id and
          trigger.to_state.context.parent_id != this.context.id)
      }}

actions:
  - action: homeassistant.turn_{{ trigger.to_state.state }}
    target:
      entity_id: >
        {{
          expand(linked_entities) |
            selectattr("entity_id", "!=", trigger.entity_id) |
            map(attribute="entity_id") |
            list
        }}

@dbrand666, sorry, I made a typo. Step 4 is for "light 1", not "light 2".
The issue is only observed when using physical switch. When controlling the lights from HA dashboard everything looks ok regardless how quick the lights are toggled.
I'm using Inovelli Smart Dimmers.

I tried traces but they are a bit confusing. I will experiment bit more today, but it looks like the "3rd" condition check fails and that's why the other switch goes out of sync.

@dbrand666, sorry, I made a typo. Step 4 is for "light 1", not "light 2". The issue is only observed when using physical switch. When controlling the lights from HA dashboard everything looks ok regardless how quick the lights are toggled. I'm using Inovelli Smart Dimmers.

I tried traces but they are a bit confusing. I will experiment bit more today, but it looks like the "3rd" condition check fails and that's why the other switch goes out of sync.

Same here...

I have the same issue as rubenhak above, I just came to discuss it and then saw his message. I have two lights, A and B. If they both start off and I flip the A switch, A comes on then B 1/2 a second later. If I flip A back off, B goes off.
However if I flip A on, they both go on, then I flip B off, B goes off but A stays on. Let me try it with a longer delay to see if that works (I was testing so flipping things quite fast).

The switches in this case are sonoff devices, physical switches. I don't know if A is staying on or going off then on rapidly. I think from looking at the logs (which are not trivial to understand) that A is staying on as it fails the test to switch it off.

In my case I only have two switches I care about, so I may use a simpler recipe which is explicit on 2 switches.

I have the same issue as rubenhak above, I just came to discuss it and then saw his message. I have two lights, A and B. If they both start off and I flip the A switch, A comes on then B 1/2 a second later. If I flip A back off, B goes off. However if I flip A on, they both go on, then I flip B off, B goes off but A stays on. Let me try it with a longer delay to see if that works (I was testing so flipping things quite fast).

The switches in this case are sonoff devices, physical switches. I don't know if A is staying on or going off then on rapidly. I think from looking at the logs (which are not trivial to understand) that A is staying on as it fails the test to switch it off.

In my case I only have two switches I care about, so I may use a simpler recipe which is explicit on 2 switches.

Exactly the same happens to me. I hope they can fix it

This simple task turns out to be quite problematic.

I'm linking two basic Tapo switches using this blueprint. It works, slowly (multi-second delay much of the time), and sometimes it fails to turn on the second light altogether. This is the error I'm getting in that case:

Stopped because an error was encountered at June 17, 2025 at 8:58:01 PM (runtime: 9.54 seconds)
Unable to communicate with the device async_turn_on: ('Unable to query the device: 192.168.68.91: ', TimeoutError())

This task works perfectly and fast when implemented via the Tapo app.