ORD - HKG (Transit only) - SGN - HKG - PVG - HKG - ORD

I am flying to Vietnam (SGN) from Chicago via HKG (transit). On my return from SGN to Chicago I plan to stop of in HKG take an internal flight to PVG and return to HKG within the 72hr period and continue my flight back to Chicago from HKG is this allowed under the 72hr visa program?