Here's another twist on the interna1tional upgrade issue that affects flights operated by CO that are codeshared by other airlines. Some of these codeshare arrangements involve "hardblocks", where the other carrier buys a certain amount of seats in advance for each flight. I believe that the Air France codeshares with CO are this way. So, AF has already bought a certain number of BF seats on each flight. If AF doesn't sell them, and doesn't release them back to CO, they will go out empty, even if there are CO customers on the upgrade waitlist, as CO doesn't control the AF seats. Since the EWR-LGW CO flights have Virgin codeshares on them, many of the BF seats that show as unassigned on a seatmap will be under Virgin's control, and may not be released until day of departure. Reportedly, Virgin is much better at releasing unsold seats back to CO by day of departure than AF is.

Codeshares with other airlines may not use hardblocks, meaning that the other carrier pays the operating carrier for each seat as they are purchased. In this case, the operating carrier can release all remaining seats for upgrades at the time of departure.