These route when I search between Stockholm ARN - XXX on different dates.
(not booking only below-mentioned sectors)
for example:
Bangkok - Hong Kong on TG
Chicago ORD - Los Angeles on UA
Brussels - Leeds on BD
Newark EWR - Toronto YYZ on AC
Beijing PEK - Shanghai SHA on CA
Zurich - Geneva on LX
Copenhagen - Wien on OS
Stockholm ARN - Beijing PEK on CA
Stockholm ARN - St Petersburg on FV
These routes are not showing as optional destinations.
Frankfurt - Almaty on LH
Frankfurt - Addis Abeba on LH
These SK coded flights are bookable on
Wideroe site.
Are you really able to book CPH-VIE (just that segment) on the Wideroe site? I think that route has traffic restrictions making it only possible to book together with another SK (long haul) segment.
Another route is ARN-FRA for example. You must explicitly click "show more departures" to see the code shares. Not really user friendy.