I am currently in the process of researching flights from DRW (Darwin, Australia) to TLV (Tel Aviv, Israel).

It am currently considering an itinerary with the route DRW -> SIN -> FRA -> TLV with the DRW -> SIN leg being with SilkAir and the rest with Lufthansa. I have not been able to find this itinerary on airline websites, only third-party websites, e.g. Orbitz.

I have been trying to understand in what cases I would need to pass through immigration/border-control in connection airports, rather than just being able to stay “airside” the entire way. From my research so far, it seems that if my booking is under a single PNR, then I would likely be able to be checked in for all the flights at the first airport, and so would be able to just remain “airside” the entire way, in SIN and FRA.

Now what I am trying to understand is whether booking through third-party websites will in fact produce a ticket which is under a single PNR. For example if I book through Orbitz, though it’d also be helpful for me to know whether that is the case in general.

So the question is whether booking through third-party websites will in fact produce a ticket which is under a single PNR, mainly in the case of Orbitz, but a more general answer would also help.

How I got to this itinerary is that I used Hipmunk to search for itineraries, and then it led me to Orbitz. On the Orbitz online booking pages, I do not see anything about PNRs or whether it is a single “ticket” or not, or anything like that. It just lists the flights and asks for my details. It does link to a Terms & Conditions page but that page doesn’t seem to say anything about this issue.