James Bevan of Hereford C 1817

I have all the information on the descendants of James Bevan b. abt 1817m married Ann Jones in Merthyr Tydfil, Wales, Feb 1838, and immigrated to Australia 1842, with their two sons William (3) and John one and a half.

What I am now looking for are the parents of James and Ann and any of their siblings. I have been hitting the proverbial brick wall with my research and would appreciate any help to try and trace the parents or siblings.

Bill Bevan