Upvote:1
A fair number of airline websites offer what is called 'multi-city' booking/search option. You can create all sorts of routings, but need to consider that the airline you are searching might not serve all the city pairs.
You maybe be able to use the alliance websites to create a multi-carrier itinerary.
The OTA (online travel agencies) may offer a multi-city option that can stitch together different airlines.
A tradional travel agent can also stitch together itineraries using multiple airlines.
BUT .... the airfares these last three use may be related to one way fares, because fare rules are often not combinable across two unrelated airlines.
Upvote:7
Norwegian Air Shuttle specifically only sells point-to-point trips - in practice, this means that rather than making one-way trips artificially expensive (and in exchange maybe having slightly cheaper two-way trips), which is what most airlines do, your itinerary has no effect on the prices. So there is no need to look for a multi-city or two-way option; there isn't one - but rest assured that that doesn't mean that their one-way trips are unnecessarily expensive.
Like Tom, I would recommend checking prices with e.g. Hipmunk, but if Norwegian does serve the involved destinations, you'll see that their "one-way pricing" usually is pretty competitive.
(Disclaimer: I am from Norway, and so I have some interest in promoting Norwegian companies, but I am otherwise unaffiliated with Norwegian Air Shuttle.)