Originally Posted by tris06

I know Delta members get some additional benefits on KLM/flying blue and vis versa but he is asking from the perspective of China airlines dynasty membership which has no additional treatments in this case.

The only additional bits he would get is by flying China eastern/China southern or Xiamen airlines domestically. In that case he would get domestic lounge access and being able to invite one person with him as a guest.

So to finalize it he will be upgraded after KLM and Delta elite members.Again his chances are very very slim. And this is not guaranteed but its logical assumption by many members here and there.
Its not even worth talking about upgrades to be honest in this case because its just that unlikely.

I would like to add though.. which is a small thing anyway. That on my last small flight from London-Amsterdam they did allow me to use the economy comfort seating. With 3-4 other members of KLM or etc. Where the back of the plane which was normal economy was really full.