Help with automation for extractor fan / cooker hood

I am new to homeassistant and struggling a bit with creating an proper automation for controling our extractor fan / cooking hood.
I have the following situation:

  • the cooking hood has 4 states (1,2,3,4)
  • one KNX entity for “1 up”
  • one KNX entity for “1 down”

What I want:

  • controlling the cooking hood via Alexa as a fan or switch with “percentage”.
  • saying something like “Alexa set cooking hood to 50%” should sent a “1” to KNX entity “1 up” TWICE (first 1 for 25%, second for 50%)
  • homassistant should know and save the state of the cooking hood

Question: do I need a “dummy entity” for this?

I do have an integration in JavaScript. So I would know how to build this in Code. But the homeassistant approach is new to me, and I have no idea how I can build this out of entities, helpers, automations, blueprints etc.

Hope I did make clear what I need and would be happy for help.