Originally Posted by
Ditto
If it is vital for you to fly in J for the KUL-AMS, you should book that segment in J, that is the only way to guarantee you fly in J.
Maybe I have overstated it by saying "vital" but thanks for the obvious reminder Ditto.
If I could I would buy right away an upgrade only for that segment. Been in touch with KLM on online chat, and they can only upgrade the whole ticket (LIN-AMS-KUL-AMS-MXP), which is unnecessary for me.