I have a NW ticket MSP-EWR for Saturday then EWR-ATL-MSP for next Tuesday. Was upgraded on the NW flight a couple of days ago and just received a call from DL that I was upgraded ATL-MSP for next Tuesday (still requested for EWR-ATL). A mix of NW/DL flight numbers all booked on nwa.com and so far so good. Unfortunately I am going to do a SDC or standby to return on an earlier flight to MSP on Tuesday.
John