All I can say is that if the offer is accepted, they will re-ticket and your e-ticket number will change. They will also take over "ownership" of the booking from a travel agent, if that's how you booked your flight in the first place. Might not matter to you, but an annoyance for me when I tried to change the return leg of a flight after PlusGrading the outbound and my travel agent told me they no longer had access to it.