Thanks for your responses. I did check ARN-FRA, which is operated by LH and you get the same with one GO option and SAS Plus Pro. There you get a seatmap so it's 100% clear that SAS PP is business. Danielstrandby, I did not see any indication of booking class prior to purchase. (Why can't they show a simple thing like that?) This also made me wonder what happens to the FRA traffic in September....... I guess SAS will have to start flying there but will be quite limited. Will flights to CDG and AMS become AF/KL only, I wonder?

It's interesting that this "discounted" business is refundable whereas with TK you have to pay a small upcharge to make it refundable and the ticket is about 40% more expensive. Also, on the following day there is no availability in SAS Plus Pro for IST-CPH. So the SAS codeshare in business is just this cheaper fare or nothing, it seems. On TK the pricing is uniform for all these flights; they have 4 per day. Also, one flight is completely omitted as a codeshare via SAS.