Hi
OK, then I will suggest this as an alternative:
Jun qtr 1868
Edwards Samuel Merthyr T 11a 527
Jones Ellen Merthyr Tydfil 11a 527
Lewis Thomas Merthyr T 11a 527
Richards Sarah Merthyr Tydfil 11a 527
1871 census
Gelligaer
Samuel Edwards head m 31 laborer in a coal mine Shrewsbury
Ellen ditto wife m 30 Llanross
Robert J ditto son 2 Glam Gelligaer
William Jones boarder m 34 coal miner Cardigan Kilcenin
Robert ditto unm 14 ditto ditto
John ditto ditto unm 12 ditto ditto
[If the marriage is correct then these Jones may be related to Ellen]
Then perhaps Ellen/Eleanor died
Death Jun 1874
EDWARDS Eleanor 33 Merthyr T. 11a 358
And Samuel remarried
Marriages Mar 1876
Campbell Ann Maria Merthyr T. 11a 462
Davies Catherine Merthyr T. 11a 462
Edwards Samuel Merthyr T. 11a 462
Matthews John Merthyr T 11a 462
1881 census transcription details for: High Street, Ruardean (Gloucs)
National Archive Reference:
RG number: RG11 Piece: 2586 Folio: 70 Page: 24
Address: High Street, Ruardean (Gloucs)
County: Herefordshire
EDWARDS, Samuel Head Married M 40 1841 Shoe Maker Shropshire
EDWARDS, Catherine Wife Married F 34 1847 Doulas Glamorganshire Wales
EDWARDS, Robert J Son Single M 12 1869 Scholar Doulas Glamorganshire Wales
EDWARDS, Margaret J Daughter Single F 9 1872 Scholar Doulas Glamorganshire Wales
Margaret J Edwards was unmarried in 1901
1901 Brynmawr
220 Robert J Edwards Head 29 abt 1872 Male Dowlais Monmouthshire Wales
220 Sarah A Edwards Daughter 4 abt 1897 Female Brynmawr Breconshire Wales
220 Francis M Edwards Daughter 3 abt 1898 Female Brynmawr Breconshire Wales
220 Maggie J Edwards Sister 28 abt 1873 Female Dowlais Monmouthshire Wales
If you can splash out on a birth certificate for Robert then you will know who his mother was. I don't think that there is any other way to do it