Once on an Air India plane many years ago, I happened to have a terrible migraine headache and had a seat in front of the movie screen. Fortunately, the flight attendant allowed me to go have a seat in business class. While I had been in economy, I noticed a young woman who came and put her belongings in the overhead cabin and took a seat. After a few minutes, she got up and walked towards the front of the plane. When I was in business class, I noticed that she had found herself a seat.
My question is, whether flight attendants really check or aware of which seats are empty in business/first class. ( I assume they have a list of names accorded to each seat) Also, do they need permission from the cabin service manager if they do want someone to sit in business/first class?