James and Rebecca MARTIN 'Champion of the Seas"

I have found that my family James and Rebecca Martin came to Australia on The Champion of the Seas arriving in Melbourne on18th November 1864. I am looking for any other families who immigrated with them as I am unable to find any birth records for James, or his three eldest children Thomas, Robert and William. The fourth child John James was born in Ederny in July 1864, 2 months before they sailed from Liverpool. Finding other families may help identify where they wer living before they immigrated and perhaps birth dates and place. Thanks Jennie