Thanks on how to use the AC and ANA sites!

Possibly a dumb question, but I noticed F-savers are very numerous. Is it possible for me to get 2 F-savers and once on the plane ask the FAs to switch my two F-seats with 2 passengers in C?

I highly doubt I couldn't find two C passengers willing to move-up to F in exchange for me moving down to C, but is this allowed?