I believe that BigjetLiljet question was in regard to FE's or more specifically PFE's upgrading to the right seat. In this case there is a world of difference between the SO (Second Officer - FE, a pilot versus a A & P mechanic in the case of a PFE), upgrading and an FE.
I know that there has been a few upgrades at some of the 74 ACMI operators out there. It would probably be on a case by case basis at this point in time.
Some operators in the past routinely upgraded PFE's if they met specific requirements, Emery was one of these. I don't think that currently there are any outfits that offer PFE upgrades with any regularity.
Good Luck!