Hong Kong to Guangzhou to Hong Kong

Hi
We are from New Zealand and will be spending some time in UK/Europe before spending one week in Hong Kong (flying Rome-Dubai-Hong Kong). If we arrive in Hong Kong and then fly direct to Guangzhou and then fly back to Hong Kong within 72 hours, are we eligible for the 72 hour Visa? (After a few nights back in Hong Kong we then have flights booked back to New Zealand).