Originally Posted by
YOWgary
The way it's written on the website, I can simply call in at T-23:59 from my first segment, and change (for example) LGA-ATL-BNA to LGA-DTW-BNA, as long as there's space open in my same fare type.
That's not correct. In addition to the fare bucket (not just fare type) requirement that has been noted, your purchased fare must also permit the desired routing between origin and destination. (A DTW connection may well be permitted LGA-xxx-BNA -- I'm making the point more broadly.)