Flight out of Shanghai goes first to Hong Kong

Hi there,
I plan to fly PARIS-SHANGHAI (to visit a friend) then SHANGHAI - AUCKLAND via HONG KONG.
The flight to HONG KONG will be with a seperate airline; I won't stopover there, only for transiting to another airline.
Do I need to include the Hong Kong flight-time within my 72 hours, or can I use the whole 72 for Shanghai? Many thanks!