Create two-way entity for 3-state light (off, dimmed, on)

Configuration
1

Hello.

I have connected a lamp to a fixed value dimmer and voltage via KNX actuators.
If, for example, channel 1 is switched on and channel 2 is off, then the lamp is dimmed.
If channel 1 is off and channel 2 is on, then the lamp is bright.
If both channels are switched off, the lamp is off.
Both channels should not be switched on at the same time.

The channels can be accessed individually via KNX integration.
Now I need an entity that switches the individual channels in both directions.
So something like a drop-down list with the entries “off”, “dimmed” and “on”.
In addition, the entity should be changed accordingly if the KNX channels change accordingly.

What is the best way to implement something like this?

Greetings

2

I am in the process of switching from iobroker to home assistant.
Is it possible that my plan cannot be implemented with home assistant?
Is my question perhaps not clear?

I would like to implement the following table in home assistant:

image

This table should be handled in both directions:
If input_select.lamp is changed, the both light entities should also be changed.
If the light entities change, the input_select entity should be changed.

Perhaps there is still an answer as to how I can meet my requirements.

3 
alias: Two lights to Input Select
description: ""
triggers:
  - id: light
    trigger: state
    entity_id:
      - light.lamp_bright
      - light.lamp_dimmed
    from:
      - "on"
      - "off"
    to:
      - "on"
      - "off"
  - id: select
    trigger: state
    entity_id:
      - input_select.lamp
    not_from:
      - unavailable
      - unknown
    not_to:
      - unavailable
      - unknown
conditions: []
actions:
  - if:
      - condition: trigger
        id: select
    then:
      - variables:
          bright: "{{ 'on' if trigger.to_state.state == 'on' else 'off'}}"
          dimmed: "{{ 'on' if trigger.to_state.state == 'dimmed' else 'off' }}"
      - action: light.turn_{{ bright }}
        target:
          entity_id: light.lamp_bright
      - action: light.turn_{{ dimmed }}
        target:
          entity_id: light.lamp_dimmed
    else:
      - variables:
          bright_dimmed: >-
            {{
            (states('light.lamp_bright'),states('light.lamp_dimmed'))
            }}
      - condition: template
        value_template: "{{ bright_dimmed != ('on', 'on') }}"
      - action: input_select.select_option
        metadata: {}
        data:
          option: |
            {% if bright_dimmed == ('off', 'off') %} off
            {% elif bright_dimmed == ('on', 'off') %} on
            {% elif bright_dimmed == ('off', 'on') %} dimmed
            {% endif %}
        target:
          entity_id: input_select.lamp
  - alias: Short delay to avoid self-triggering (probably unnecessary)
    delay:
      milliseconds: 100
mode: single
4

@Didgeridrew Thank you very much!