Yeah, my dad has tried that. It doesn’t work. Every ticket has to go through the gates at that park in order for the ticket to be able to redeem FPs. So if the rest of the party went to Epcot that morning, then one person can’t run over to MK and get FPs. However, I wonder if everyone goes to one park in the morning, then some people leave the park and give their tickets to one person if that person can then still redeem FPs in that park. I bet that works, since they don’t actually track you leaving - only entering.
Perhaps, if they aren’t running the finger scanners (which they don’t do at the busiest times - park opening), then you could enter, leave, enter, leave, enter, leave until you have activated all of the tickets. You would have to be really bored, though. I suggest that you just go hit EMH every morning and have fun by yourself.