Multiple Entry Visa / 72 hour visa

Hi we are flying into Guangzhou with a side trip to Xian airport on our return flight, details as listed. Do we need a multiple entry Visa? Are any of these stopovers included in the 72 hour free transit. Our party consists of 2 Australians and 1 from the United Kingdom.

Arrive Guangzhou / CAN Monday, 02 July 18:05
Depart Guangzhou / CAN Tuesday, 03 July 09:30

Arrive Guangzhou / CAN Friday, 03 August 16:45
Depart Guangzhou / CAN Friday, 03 August 19:25

Arrive Xian / XIY Friday, 03 August 22:00
Depart Xian / XIY Monday, 06 August 16:00

Arrive Guangzhou / CAN Monday, 06 August 18:50
Depart Guangzhou / CAN Monday, 06 August 21:25