hello ann,carolyn,thank you for your responses,its all becoming a bit clearer for me now. just to recap,the edward and hannah family appear to be as follows,[using census records]
edward hannahnee cairn. thomas william john elizabeth  luke this family recorded at anchorage row adjacent to ELVET PIT 1841 census. phoebe hannah 2 children extra on 1851 census,at new row,WILLINGTON. family listed wrongly as SHEW>
isabella edward2 more children at sherburn road,durham. on the 1861 census.
this makes nine children in total,listed on census as such. b/dates are +/- one year. caution appears necessary as other Thew families in durham city and were also miners
my knowledge[apart from ancestry.com]comes from my mother nee beatrice thew  who had heard of isabella  and edward .
the eldest son thomas does not appear after the 1851 census he was a miner also. i shall try other ideas to find out what happened to him,i live not far from the durham records office which may have further information of what was going on in county durham between 1850 - 1876 [johns arrival in aust]i.e.emigration of miners. the most likely scenario was that he went to aust.as a miner ,possibly via another country.poss a crew member any ideas?