I thought I'd follow up on our outbound. Has some interesting points.

My girlfriend can occasionally get unreasonably scatter-brained. Saturday we were flying LAS-DFW-LHR, dp. LAS 2:15 and DFW 5:00. Plenty of time for FL and FFD. However, she left her house late and missed the 2:51. OK, so they rebooked her on the 5:00, she might not be in F and she definitely won't get FFD, but at least she'll get there. Except that she missed the 5:00 too.

At this point it gets a little hazy. AA rebooked her on LAS-ORD (redeye) and ORD-LHR (redeye), meaning a 12-hour layover in ORD. I found a BA nonstop at 10PM and booked her on that, but we had a cascading series of misinformation about what was going to happen to her bags. Would they offload them in LAS if she wasn't on the flight? Keeping in mind that the flights from LAS leave at 10PM (BA nonstop) and 11:45PM (AA connection from hell) and that my flight out of DFW departed at 9PM PDT, I was going to have a several-hour gap of being out of touch.

So when I get up in the morning I find out that she bailed on both flights, her mom picked her up at the airport, and they're both at my gf's apartment and I'm on the verge of just flying home and I'm trying to find flight options and some flights keep appearing and disappearing.

And amazingly, in the end it ends up relatively decent.

1) As of Sunday evening, the changed AA ticket was no longer showing the LAS-ORD segment but was showing ORD-LHR.
2) However, the bag tracking system is showing her bags have been offloaded in DFW! (A lot of the problem was them giving conflicting answers about what would happen to the bags, and either S didn't ask or they wouldn't retrieve the bags so she could check them in for the BA flight, even though she had at least four hours to do so.)
3) As the flights kept appearing and disappearing, I did find one on BA274 (the LAS-LHR nonstop) with W space. Yeah I got nicked for around $6-700 in fees, but it was 40K miles which seems reasonable, and...
4) Once that was confirmed, I was able to get back the 90K miles I used for the original F ticket as well as the miles for the BA flight the night before.
5) And finally, the bags were flown on AA from DFW to LHR! So in the end, AA flew bags LAS-DFW-LHR for a pax who never even boarded an AA flight.

Update (forgot to hit Post earlier)

The bag story may be helpful to some. S arrived at the airport about 40 minutes before the original DFW departure. The airport was quite empty; it took me 30 minutes from getting out of the Uber to getting to the gate, so if she hasn't had to check anything she would probably have (barely) made it, but nobody can fault the ticket counter for refusing to accept her bags 40 minutes before the flight. I think she checked them in for the 5PM flight and they were loaded at 4:37, but she - again, missed the flight. The bags however went to DFW. I was in an AA chat and the chat agent (human) told me that her bags had gone to ORD. Anyway, the bags got to DFW when S wasn't there, and they didn't put them on my flight but they put them on an afternoon flight the next day. They arrived around the same time on Monday morning that the ORD flight did, although she didn't arrive for another 6-8 hours.

Normally I'd have said "I'll meet you at baggage claim" but on an international flight it's not that simple of course. When I got to LHR (about the same time S did) I found a courtesy phone in the landside area to call what I think was a third-party company handling AA's luggage issues. The person told me that the bags were there and that S had to get them (fine), but that she had to contact BA. Huh? Sure the terminating carrier is responsible for bag issues, but when your bag has never even been on their metal? Anyway, once I met up with S I had her call the same number, and BA took her into the secure area to get her bags.