Oh ok thanks. I went to the CX website and it only prompts you to pay but didn't ask for any passport information. We plan on taking the high-speed rail from Beijing to Shanghai so I think that won't be a problem.
Do you know whether the information that I use when I online check-in for JFK-HKG (using USA passport credentials) will be seen by the Chinese authorities when I online check-in for HKG-PEK and PVG-HKG though? My family is worried since the trip is under one booking reference number since it's multi-city.