HK isn't really buggy friendly, especially in Central where pavements are narrow and crowded and its hilly. Best idea would be to use a baby sling/carrier like Baby Bjorn and put your first child in a light easily foldable stroller like a Maclaren. It will depend on what areas of HK you plan visiting, places like Discovery Bay are much more Buggy/stroller friendly. But on the island I wouldn't want to take anything big and heavy.