Even SE would not save you on this one. You are trying to change the rules and they are not playing.
Not trying to change or break any rules... I'm asking for them to change the flights and quote me a change fee but "it is impossible!"
This doesn't make any sense, I can't understand how these agents keep screwing this up. You might try asking them to cancel the existing FLL-YUL and YUL-YYZ segments then add FLL-YOW.
What they come back to is that P space is no longer available. I am, of course, holding the last P space seat. I don't want to just walk away from the flight in YUL (in case their system identifies me as trying to pull a hidden city thing), but I *tried*, their agents are just generally incompetent... as I said "fine, tell me what the up-fare is". "It's not possible to have a business and economy flight on the same booking".
SMH.