I think a bit of googling would help here. If your uncle was a POW why not start by searching POW records from 1941-1945? It could not be any other dates. Assuming your aunt landed up in Australia because she had fled the Japanese invasion there is hardly likely to be a passenger list for a ship crowded with refugees fleeing from the enemy. Again the date has to be 1941-42. However I would have thought there should be a list of such people if they landed in Australia - what about "Refugees from Hong Kong/Japanese in Australia" - endless variations on such a theme - could throw up something. Generally speaking "passenger lists" are more likely to record leisurely routine runs.