In the past, this worked so well. For more than fifteen years, I've been doing at least several TATL RTs on NW with connections through AMS on KLM's short- and medium-haul business class. The NW PE agents always were careful to tell me and document my KLM confirmation number. They always got me good seats in advance, either at the time of booking (although I usually could not later change the seats myself on line or see the seating map, just see my own seat assignment, but the NW PE agent could apparently see the entire seat map because I remember discussing what was available at times) or by requesting the seat type very specifically (probably because it was too far out) and having it later show up as requested on my NW reservation. It was always "one phone call" shopping for the entire transaction, including all documentation and all seat assignments for my trips.

It's shocking but understandable that DL's IT mess has become so bad that KLM refuses to deal with it. How sad that DL is destroying the successful joint arrangement with KLM that NW had developed and nurtured over the years to the benefit of both North American and EU based passengers.