transit in HKG

Hi, if I travel from Spain via HKG to CAN airport and back from any ferry port to HKG again, using HKG as transit for both outbound and inbound flights do I qualify for 144 hours visa free transit? Not sure if transit in HKG is considered as staying in China or returning to a third country (Spain) as HKG is only the transit.
SEcond scenario.. What if I stayed for few days in HKG either on the departure or the return? Many thanks