I have a trip coming up that has to be 3 segments. The middle segment is CLT-PHX and the time that works is sold out in First. I'd purchase F for the whole trip, but refuse to pay F price for an economy seat. Further, I really want the third segment (PHX-ANC) in F, so I'm willing to buy that. Can I buy XXX-CLT-PHX in economy as one ticket, then PHX-ANC in First? There would be approx 1.5 hours layover in PHX. What happens if I'm late arriving PHX - is it treated the same as a single ticket?