Just in case you wonder where I got that info on free seats for Elite plus, here is the presentation:

https://assets.ctfassets.net/8g77hrv...september.pptx

See the third slide where it says in line 12 "Preferred seating":

"benefit extended to SkyTeam ElitePlus who will enjoy free seat selection on SAS (similar to EBG+ today on SAS)"

That said I am still struggling to successfully enter my FB number into my reservation - I probably give it a few days before I call SK to add that manually.

Greetings - Dirk

P.S.: this file is linked directly from this SAS webpage.