indeed_sushi If you book KLM light fare on KLM metal, then when you manage your trip right after booking you can select the free upgrade to KLM Economy comfort seat as STE+
It does not extend to your companion - they must be STE+ themselves to enjoy it.

On AF you can only select front section (or exit row) seats as they do not have comfort class at all

However, MQD earning will be terrible on a light fare.