A friend of mine is flying HEL-NRT-xxx soon. HEL-NRT is operated by AY, and NRT-xxx by non-oneworld members. Under AY code for the AY op flight the only option was Eco seat on NRT-xxx. Booking using JAL, the whole trip will be in C cabin.
Finnair wasn’t able to sell a ticket where the longer flights are operated by them. No double points, not even 150-250%..