Sorry to bring up an old thread. I am currently in the process of doing this. I have an F (O) seat on LH for SIN-FRA but the same route is flown by SQ. Currently, there are no open seats even to SQ's KF members, but when availability opens up for 2 I would like to call CO and have them do a "manual sell" or "long sell". What exactly should I tell the rep? When I say I want O on the SQ flight they tell me it's not available. Should I tell them to request it anyway? It'll certainly come back denied. Will SQ approve it within 24 hours? Or is it something that the CO rep needs to actually physically call the SQ desk and ask them to release 2 seats into O so that the rep can "short sell" it?

Any help on this topic is greatly appreciated.