Who taught this nonsense?
My flight school and my fellow FI on the continent when I was doing education according to JAR.FCL. As a strict rule we were taught a flight conducted does have only one filing and it has to be determined in advance on the ground, same as who is PIC, as part of a thorough flight preparation. I have to admit, I did not check the EASA changes and with common AFIL now there may be some change in it.