Hello. I'm back with some questions on change or cancel options for a new flight. Previously, we had booked a Europe flight that we had to cancel as a conference was cancelled. We got FFC for it under let's call it itinerary ABCD. We used the FFC from ABCD for a round trip (IAH-PTY[q], then PTY-SAL[k]-IAH[w]) with the PTY-SAL being Copa and SAL-IAH on UA - and all booked through United.com, and still have $ leftover on the FFC under ABCD that has to be used by 12/31/23.

I noticed a price drop (booked a week ago so 24hr window is gone) of $160/person today and started researching the ticket T&C and this site. I'm not 100% sure on the easiest process to try to get that $160/person back without fees or paying extra. Since it's a new booking, we got a new itinerary, let's say WXYZ.

-Would the best way be to cancel it completely, and get FFC under WXYZ and then rebook the exact same flights using the FFC from WXYZ leaving FFC of 160/person?
-Or is it just easier to change it as it states "If the new flight is priced lower, the customer may change without paying a change fee, and standard fare tickets may be given residual value in the form of a future flight credit."? (I'm guessing this is not allowed since it's not a "change" in any flight but just trying to get the reduced fare).
----If they do not allow a cancel or change to the reduced fare for the same flights, I noticed that we could change to cheaper flights that same day that we do not want to take since it's not direct on the way there (by about $600), but then would we get that fare difference, then be able to change it back to our original flights and still end up saving $160/person?
-If cancelling, is it allowed to book the same flights using the WXYZ FFC? (We do not have enough leftover in ABCD to rebook the flight PTY trip without dipping into WXYZ. or using ABCD and paying more from a credit card.
-We have no status, and it's not basic economy. It's also not to Mexico or Caribbean (or does Panama count?)

If all that worked and we have FFC under 2 difference itineraries, would we be able to book a trip to SEA, for example, and use the FFC from both itineraries to pay for the SEA trip?

Thank you all!