Recently, I've been watching YouTube videos of people reviewing First/Business Class seats/suites. I noticed that on some of the airlines (mostly non-US) airlines, there is a "companion" seat within the First/Business Class seat/suite. This companion seat is usually across from the tray table and from the video reviews, is meant for guests to visit you.
Therefore, is it possible for 2 people to fly together and have Person A buy a First/Business class seat/suite, but have Person B buy an economy seat and then have Person B join Person A for meals and other First/Business class amenities?