Booked the following w/Expedia a few weeks ago.....

DL FLL-JFK
UA JFK-LAX-OAK

Used UA miles to upgrade JFK-LAX-OAK.
Received schedule change info yesterday for the DL flight FLL-JFK. Now leaving an hour ealier. Disembarking from a cruise ship in FLL the same morning and will *not* be able to make the DL flight due to clearing customs/immigrations, etc.

Ticket number indicates issued by DL (makes sense, since they're the originating carrier).

Taking the next later flight on DL FLL-JFK will result in a misconnect situation in JFK to UA.

What are my options?

Since I cannot reschedule any workable options via the original routing (via JFK) I would simply like to fly Delta all the way (FLL-ATL-OAK). Will Delta be all too happy to rebook me the entire route with them, snatching the revenue from UA? If agreeable to that, will my miles spent to upgrade on UA automatically go back into my account once the UA space is cancelled?

Is rebooking due to schedule changes basically a "free for all" or are you fairly restricted?