I appear to be in a similar situation. As a newbie at international travel and award travel, let me ask these questions:
We just booked a trip to Europe (on Thursday). We're using miles to go Delta One BOI-SLC-LHR on 11/12, and CDG-LHR-SLC-BOI on 11/18.
Trying dummy bookings, the non-stop SLC-LHR on 11/12 (Sunday) appears to be gone. I haven't looked at the return options yet.
Delta.com shows BOI-SEA-LHR (SEA-LHR on Virgin) as being available on 11/12. However, to get in Delta One/Business the tickets show as available if we pay cash, but not available using miles. Can we get switched to those flights?
Second option, a day earlier (11/11) shows our original BOI-SLC-LHR flights as being available, but it costs 135K miles for Delta One instead of the 70K we originally used. Can we switch without using more miles?