Change flight to evening before ticketed
 

I think I know the answer but what other options do I have.

I am on a personal flight home @ 5 a.m. SEA-FLL-via DFW arriving back at 4:06 pm on a Tues. O fare - r/t ticket was a tad over $300. This was more or less a mileage run.

Just found out I have a work trip I can do in LA Tues - Friday. (would love those extra miles). Would need to fly out Tuesday

I would love to take the direct Mon 11 pm red eye SEA-MIA home and just turn around and reboard (think miles; here no being of sound mind). Even though just 6 hours prior to my ticketed flight, I do not believe they would consider that same day, correct? And will want to charge me, regardless of status, $200 + change of ticket price which is much higher. Correct? Not the $75. So that seems out of the question. There isn't an issue changing a destination from FLL to MIA, correct?

Other Options:
If I abandon my return to FLL - how is that viewed by AA? Because obviously I can have my work ticket from SEA-LAX and then LAX - MIA. or even fly one portion of my personal trip SEA-DFW (then abandon the DFW-FLL portion), turn around in DFW back to LAX on my work ticket. There are no flts from FLL-LAX, so even if I flew my pesonal ticket back on Tues, I'd had to then get a taxi to MIA to fly to LAX, sounds exhausting.

Will AA even allow overlapping tickets? Or will they cancel one or both.

I'm not trying to circumvent AA policies, I would really like to go on this work trip without really affecting my personal travel too much. Ideally be able to keep the two travels separate.

You can't book the work trip without the danger of AA's detecting the overlapping flights and cancelling one. You can try not including your FF number, but sometimes corporate travel systems include FF numbers automatically. You could fly on a different airline, but it sounds like you want to earn AA miles, so that would defeat the purpose.

You could cancel all or part of your return to FLL, but what would you do if your business trip were to be changed or cancelled at the last minute? You would be stuck without a ticket home.

I would keep the trips separate. Yes, it will be exhausting to cab it to MIA after your arrival at FLL, but sometimes mileage runs are like that. :)

Sometimes an after-midnight redeye is considered part of the prior day, but that won't be the case here. Sorry.

Don't shoot me if I'm wrong, but I wouldn't worry too much about an overlapping flight on the return. People's plans change. Has anyone ever heard of an "overlapping" flight actually being cancelled? Do airlines actually bother writing software to scan for that? The same airlines that can't even figure out that they have 2 seats in F left and 3 high-status pax, so they give them to a low-status pax and his pet gerbil on an award ticket?

Yes, plenty of folks have had overlapping flights cancelled. In some cases AA has called to ask which one they want to keep and in other cases AA has just cancelled whichever one they see fit. So, there is a true risk of losing the flight you want.

No worries. The boss wouldn't let us travel to LA for this job anyway. So no stress now on my return home.