Ok I think (think) you are suggesting:
Haste II
Dualega which is supposed to give 15% attack boost to party members
Endow which is supposed to...let us cast...either 2 songs at once or cast a gain spell and an en-spell...I think...
For dualega and haste II I don't see why they would say no (some might argue the haste cap is the reason it isn't in the game) but endow um either scenario might be denied because casting 2 at once is, as far as I know it, haven't been done with any other job.