Originally Posted by
schriste
There is that 1 compartment with 3 seats. I imagine you could buy 3 tickets and reserve the seats to protect your privacy. I’d imagine you can book the 3rd or 4th ticket for “a friend” that did not show up

. If the train is packed beyond belief I guess someone might try and take your empty seat and you would then need to start explaining… but I’d think this not terribly likely.
Business class on railjet requires seat reservations, so it's not possible for people to just choose to sit there because it's empty