Many Hong Kong families emigrated to Australia, so you might find these old immigration cards from your family members if they travelled to Australia until 1972, when these cards ceased.
Passenger arrival records from the National Archives of Australia:
Incoming passenger cards
Outgoing passenger cards
On their website is written:
"From 1948, air travel passengers filled in their own cards. Passenger lists on ships continued until 1965, when cards completely replaced lists for both air and sea travel."
Their home page is:
On the home page, click on the right-hand side on "RecordSearch" then click on the tab "Passenger arrivals".
After typing in the person's name and it appears on the list, click on "Digital copy".
When the card appears, either scroll down, or maximize the screen, and click "next" to get to the reverse side because these cards are double-sided and there might be stamps and writing on the back, as in this example which was from my aunt, Emily Low. She was married to Victor Low who was an architect with Palmer & Turner in the 1930s.
Date picture taken
1954