Set the brightness of multiple lights in automation

I want to convert the below code to use brightness_step_pct = 10 on multiple entities. what is the correct way to add a data characteristic to a group of entity_ids?

- id: 'switch-dim-up-pressed'
  alias: 'Switch dim up pressed'
  description: ''
  trigger:
  - device_id: e7c5e14a1543e2d292d565e613aec298
    domain: zha
    platform: device
    type: remote_button_short_press
    subtype: dim_up
  condition: []
  action:
  - device_id: d8481adfe9b6cd7bc4308c499273ca80
    domain: light
    entity_id: light.dining_1
    type: brightness_increase
  - device_id: 8459815ecb96667ac8e65ab61ce70e08
    domain: light
    entity_id: light.dining_2
    type: brightness_increase
  - device_id: 336e2ab5504b54a5d047efbffb6bc47c
    domain: light
    entity_id: light.dining_3
    type: brightness_increase
  - device_id: 0929cfc419aaad4bbe1ade666ede90f3
    domain: light
    entity_id: light.dining_4
    type: brightness_increase
  - device_id: 6790beb2f359768618237b15a2f80421
    domain: light
    entity_id: light.dining_5
    type: brightness_increase
  - device_id: 48aec9cc22013221dabf2042df1a182c
    domain: light
    entity_id: light.dining_6
    type: brightness_increase
  - device_id: f44bf2fa6a2e2a79e5f32f82c03e4c06
    domain: light
    entity_id: light.dining_7
    type: brightness_increase
  mode: single

This is the code I am trying to insert but currently not working.

- id: 'switch-dim-up-pressed'
  alias: 'Switch dim up pressed'
  description: ''
  trigger:
  - device_id: e7c5e14a1543e2d292d565e613aec298
    domain: zha
    platform: device
    type: remote_button_short_press
    subtype: dim_up
  action:
    service: light.turn_on
    entity_id:
      - light.dining_1
      - light.dining_2
      - light.dining_3
      - light.dining_4
      - light.dining_5
      - light.dining_6
      - light.dining_7
    data_template:
      brightness_step_pct = 10
  action:
    service: light.turn_on
    target:
      entity_id:
        - light.dining_1
        - light.dining_2
        - light.dining_3
        - light.dining_4
        - light.dining_5
        - light.dining_6
        - light.dining_7
    data:
      brightness_step_pct: 10   ### <--- note ":" not "="

You could also create a light group helper so you only have to specify one entity id.

e.g.

light:
  - platform: group
    name: "Dining Lights"
    entities:
      - light.dining_1
      - light.dining_2
      - light.dining_3
      - light.dining_4
      - light.dining_5
      - light.dining_6
      - light.dining_7

That can also be done in the UI helpers section.

Your automation would then be:

- id: 'switch-dim-up-pressed'
  alias: 'Switch dim up pressed'
  description: ''
  trigger:
  - device_id: e7c5e14a1543e2d292d565e613aec298
    domain: zha
    platform: device
    type: remote_button_short_press
    subtype: dim_up
  action:
    service: light.turn_on
    target:
      entity_id: light.dining_lights
    data:
      brightness_step_pct: 10
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