Check out re Whitfields and Christisons.
How did the Whitfields get to Australia? As Barry Allan notes in his family story Black Sheep and Gold Diggers, “Bill never mentioned that his own father had been a convict as well. It was socially unacceptable to have criminals in the family, and most families who had one invented all sorts of fanciful stories to explain how their ancestor came to Australia. These stories survived, often being embellished over the years, until the stigma faded and the truth was eventually discovered generations later.”