*I know the thread title says KLM< but this question involves Delta too. So please don't nuke this thread, mods.

Hi, Delta forum! This is my first post in this area, so my apologies if this has been answered 100x over somewhere else.

My wife and I are looking into flights to BCN next year, with a connection in AMS. (full route = SEA-AMS-BCN)

Based on our schedule and timing needs, we're seriously looking at Delta options. But one question we have is regarding lounge access in AMS - specifically the KLM Crown Lounge. Now my wife recently made a business trip to the UK, and she flew Delta business class. But for some reason she was denied access to the KLM lounge upon arrival in AMS. (oddly enough, she WAS granted access when flying Delta J-class on the way back through AMS enroute to SEA)

Based on that experience, we're kind of confused as to what the lounge rules are in AMS. So consider these two possibilities:

Scenario 1: We book a Delta ticket and fly on Delta metal, J-class. Can we access the KLM lounge?
Scenario #2 : We book a KLM ticket on a flight that's operated by Delta. Again in J-class. Can we access the KLM lounge?

Any insight is greatly appreciated. Thanks!