Originally Posted by
AlwaysAisle
Likely you were ahead of upgrade list because you purchased Pre Econ. If you had S fare to begin with then probably you would not got this J seat when C inventory became available, likely went to somebody higher on upgrade list who purchased Pre Econ. From that prospective, likely answer will be no because if such is allowed then this will become a trick to be on the top of the upgrade list.
This is not how it works at all. Economy and Premium Economy upgrades to business all come from the same "pool" of space which is sorted by status and EQD. A $20k rolling EQD EXP who buys a $500 discount economy ticket will be ahead of a $15k EQD EXP that purchased a $2000 premium economy ticket.
*the
only time fare class matters is in the unlikely event that 2 people are on the same upgrade list with the same status and exact same rolling EQD.