Lou thanks for your answer!
I have few more questions :
What were the feelings of the TWA's F/E community at the introduction of these new planes? did some F/E moved to pilot positions as a result? I'm not sure but I think that in Air France some F/E were offered pilot training.

Regarding relief pilots I was wondering : did every TWA pilot could be a relief pilot or were the most junior pilots given this duty?

And the final question : As a pilot how did you see the end of the F/E era?