Three of Robert and Ann Birrell's sons married members of the Champniss family: William married Mary Ann Champniss's younger sister, Emma, on 30 April 1838. Robert and Alexander married Sarah and Harriet - two of Mary Ann's daughters and thus Emma's nieces. They married them in 1844 and 1848 respectively.
Robert and Anne's youngest three sons all emigrated to Australia. Of these, Robert and Alexander went with the Searle sisters, Sarah and Harriet whom they had married. Alexander and Harriet married on 16 December 1848 in London and it is known that Robert and Sarah emigrated between 1848 and 1850. In all likelihood the two brothers and sisters went together along with Robert and Sarah's baby and two under-three-year-olds. The third brother, John, married in Parramatta, near Sydney, in 1850. Did he also travel out with the others and move on to New South Wales- or did he go out separately and to Sydney, rather than Adelaide? [2]