Yes, mister kia, let me help you: This does not have to be in the Amadeus portal, though this is typically tooling, created by the airline, fed with query reportings, to "help" the staff monetize on these things. And from there, just manual fine-tweaking the availability spread over the booking classes.

And, no, there were no 3-4 people booking, since the overall availability didn't decrease (nor the number of seats occupied in the seat map), only less availability in the booking class I would be interested in.