possible parents.... 1851 census at Copper Row, Michaelstone super Avon, Neath
David Thomas, married, aged 41 (1810), copper man, born Swansea
Sarah Thomas, married, aged 39 (1812), born Llangyfelach
Margaret Thomas, daughter, aged 21 (1830), born Swansea
Thomas Thomas, son, aged 15 (1836), born Swansea, occupation appears to say 'tending massons'

Mary Thomas, daughter, aged 8 (1843), born Swansea
Hannah Thomas, daughter, aged 1 (1850), born Swansea
The same family was at Copper Row in 1841
Added: this appears to be the right couple as on the 1861 census, daughter Sarah Ann, is aged 2, birth registered Sept quarter 1859 with mother's maiden name Owen. Thomas (24) is a copper smelter, Jane (25), and they are at 23 Davies Row, Michaelstone super Avon