Join Date: Oct 2000
Location: Munich, Germany
Programs: LH HON, DL FO/MM, Marriott Lifetime Platinum, Accor Lifetime Platinum, Sixt Diamond
Posts: 6,174
This is a prime example where a good travel agent would have saved the traveller lots of aggravation, time and money. Airline agents are supposed to sell flights marketed by the airline they are working for - whether it's the best deal for the passenger or not does not matter, since they are not in the business to sell tickets based on the fares filed by other airlines, including most alliance partners.
China Eastern is having a substantially better/cheaper fare structure between ATL and PVG, with the lowest published fare starting at 4920 USD plus taxes and fees, vs. Delta starting at 6440 USD plus taxes and fees. China Eastern allows interlining on the domestic flights to their LAX/SFO/NYC/ORD/YYZ/YVR gateways on many airlines - not just DL, but also AA, WS and AS - thus giving the traveller many more options.
With everything on one single ticket, odds are that through check-in should work - and in the event of a missed connection, the airline causing the misconnection would be obligated to re-route the passenger.