Yesterday I had a chat with CS on the web site. Was looking at buying a ticket CPH-HEL-HKG. When checking availability for an upgrade when searching HEL-HKG it shows available, but when searching CPH-HEL-HKG - nothing available, same date for both searches. So I asked the CS if I buy a ticket CPH-HEL-HKG, can they upgrade my HEL-HKG segment, as I really don't care about CPH-HEL, they said because CPH-HKG is different itinerary than HEL-HKG, they cannot.
The hell!!!