Originally Posted by CosmicGirl

Unfortunately that doesn't necessarily make it the truth. A few months ago I wanted to book KL-LHR/LGW-VS marketed by DL because that was the only way I could get an outbound on VS metal combined with a return on AF metal to ticket. Before booking I called and texted VS to be sure that I would be able to upgrade the VS segment if it was booked under a DL code and issued on DL (006). Both the call centre and the texting service confirmed that this would be possible, so I booked the ticket. Then, of course, when calling to do the upgrade I was told that they could only upgrade the VS flight if it was booked on a VS code, regardless of who issued the ticket.

I ended up spending more time on the phone getting this sorted than the return transatlantic flight took. It was ridiculous. In the end I found a DL agent who was willing to change the flight number to the VS code but in total it took nearly four weeks to get it sorted. And even after VS had confirmed that they had done the upgrade, one of the tickets kept having (both VS and KL) legs dropped for no reason. Two days before departure I finally thought that everything had been fixed, yet upon checking in KL refused to honour the Premium allowance and made us pay €70 to put an 11kg suitcase on a 1-hour flight to LHR. Mind you, the checkin staff had never even heard of VS. Now, months later, the argument with KL regarding this fee has still not been resolved. And upon checking in for the VS flight in LGW we were told that the one ticket that kept dropping legs still had not been issued properly. Fortunately, the VS staff at LGW fixed it promptly but as a whole it was such a mess that I vowed never to book an AFKL-VS connection again if I had any intention of upgrading.

Maybe they've smoothed things out by now but given the amount of holes still present in what was published last week I wouldn't hold my breath. If you've found a way to book AFKL-LON-VS coded as such (or all VS-coded) I'd love to hear about it but I haven't been able to.