I am in China now, having used TWOV to enter. Flew in on DL from the US. Will be flying out on LH to Europe. As risk alleviation on my part to ensure I didn’t have an agent try to deny boarding in the US becuase they were confused, what I did was I called DL a couple months prior and had an agent verify that I’d be good to go with TWOV and then had the agent place a note in the reservation that I would be using TWOV but had a departure on another airline.

You will be asked for a printout of your outbound itinerary both at check-in with DL since they won’t be able to see the outbound reservation and you will need the printout of the outbound itinerary (with the airline confirmation number) when processing the TWOV line upon entry into China.