I've searched on the Australian records for Immigration into their country for both names and there is no record from 1950 to 1960 of them arriving by ship or plane. I know they Australians are a stickler for their records being accurate, are you sure of the destination, ship and dates and I've searched those records for my own relatives and found them straight away. Both ship and air arrivals are all recorded and you can see the scanned arrival cards. There are also no records relating to them from the Immigration and Naturalization Records from 1950 to 1970, sorry.