Regarding changing D2 to D1 after check-in on D2 listing. BIG no-no. How do I know? I did it, not knowing it was against the rules. The agent told me that there is an audit trail from the time you check-in until the listing is used or becomes obsolete (you check-in, but then you don't show up at the gate, and the flight leaves without you.) What I did was check-in 24 hours in advance for my D2 listing; saw that the flight was filling up because of a cancellation; cancelled the D2 listing; relisted and checked in as a D1. Got caught. Agent I knew was working the flight. She told me that what I had done was against the rules and people had been terminated for doing similar/same. I let her cancel the D1 listing, and I went home relisted and went the next day. I later checked if what agent had told me was correct. It is.