Thanks to all. Got my answer: couldn't find anyone at DL-JFK (Terminal 2-3) who wanted to get in to the NW system, had to traipse over to terminal 4. Jumper, what are 'AS' tickets? All we, as Pinnacle parents, can get now are ZED tickets on any airline, including DL and NW. And DL & NW are Zed High. AND...can't figure this at all: the Zed tix we got for the DL (ZEDH) flt FRA-JFK are $322, while LH (also ZEDH) are $180..comparing the tickets I see a huge difference in the taxes. Bought them both, AND Continental ZEDM, so we'll be sure to catch something back to NYC on Nov. 15. Wish us luck.
And our luxury run on DL seems to be over: no more upgrading at JFK (flew to NCE), the gate agent AND cabin crew were adamant, though there was plenty of space up front. We were still happy to get on, and there was plenty of stretching room in back.