I have a question about a rescheduled flight which I was hoping somebody could help me with. First a little background.

I had to reschedule my return flight from PEK (Beijing) to PWM (Portland, Maine) from August 8th to May 11th. I was/am scheduled on Airchina from PEK to JFK and Delta from JFK to PWM (note, it was booked as one trip). I rescheduled my flight through Airchina.

Now here is where my question/concern comes into play. Airchina issued me a paper ticket with an open return anytime between May 11th and August 8th; however, they wrote in flight numbers and times for May 11th. Now when I check my ticket on DL the change does not appear (I am still scheduled for August 8th). I have called DL (the local office here in China) to ask them if I will be guaranteed a seat from JFK to PWM, and if my AirChina paper ticket will be honored, even though my flight change has not been updated in their system. They do not understand what I am asking (lost in translation). So, my question is, has anyone out their been in this situation before? Is this a common way of making a schedule change? Am I essentially flying standby? Thanks in advance for all of your help!

Thanks,
Josh