Universal Media Player Source

Hello, I am attempting to override the default HDMI sources for my TV entity by creating a UMP.
I am attempting to have it choose a button click from my Broadlink RM4 Pro to be the new Input source. Ultimate goal is to be able to tell Alexa to switch the TV to the source on my external HDMI switch.
The question is how do I achieve this? I don’t get an actual entity for filling in the source data.
What I have so far:

  - platform: universal
    name: Test TV
    children:
      - media_player.bedroom_tv
      - media_player.media_player.firetv_bedroom
    commands:
      turn_on:
        service: remote.send_command
        data:
          device: Bedroom - TV
          command: Power
        target:
          entity_id: remote.bedroom_hub_remote
      turn_off:
        service: remote.send_command
        data:
          device: Bedroom - TV
          command: Power
        target:
          entity_id: remote.bedroom_hub_remote
      volume_up:
        service: media_player.volume_up
        data: {}
        target:
          entity_id: media_player.bedroom_tv
      volume_down:
        service: media_player.volume_down
        data: {}
        target:
          entity_id: media_player.bedroom_tv
      volume_mute:
        service: media_player.volume_mute
        data: 
          is_volume_muted: false
        target:
          entity_id: media_player.bedroom_tv
      select_source:
        service: ???
        target:
          entity_id: ???
        data:
          source: "{{ source }}" #Not sure what this does
      volume_set:
        service: media_player.volume_set
        target:
          entity_id: media_player.bedroom_tv
        data:
          volume_level: "{{ volume_level }}"

    attributes:
      state: media_player.bedroom_tv
      is_volume_muted: media_player.bedroom_tv
      volume_level: media_player.bedroom_tv|volume_level
    device_class: tv 

I’m just confused as to how to tell it multiple sources

This is my command for HDMI 1 from my external HDMI switch.

service: remote.send_command
data:
  device: Bedroom - HDMI Switch
  command: Input 1
target:
  entity_id: remote.bedroom_hub_remote