This is my take on the family:
Births:
David Edwards, Q2, 1867, Machynlleth, 11b 217 mmn -
Mary Edwards Q2, 1871, Machynlleth, 11b 187 mmn Edwards
Bridget Jane Owens, Q4 1874, Machynlleth, 11b, 168, mmn Edwards
Margaret Elin Owens, Q3, 1877, Machynlleth, 11b, 170, mmn Edwards
****NW BMD has all of these births as in Darowen*****
This would fit with the marriage, given earlier:
Marriage Q3 1873, Machynlleth, 11b, 237
Owen Owens married Margaret Edwards (confirmed on NW BMD)
Possible death for an Owen Owens, aged 53:
Q2, 1878, Machynlleth, 11b, 144
NW BMD has this death as in Darowen
1881 Census
Skinner Street, Aberystwyth
RG11/5445/9/ 12
Margaret Owens, wid, 35, Washing woman
David, son, 14, apprentice painter
Mary, daughter, 10, scholar
Bridget Jane, daughter, 6, scholar
Margaret Ellen, daughter, 3
Place of birth looks like Paris (?Parish), and possibly Dorwen/Dorwen
Compare this with the 1871 census
Rhydyfelinbyrhedy, Darowen
John Edwards, widower, 57, lead miner, b. Merionethshire, Towyn
Margret Edwards, daughter, unm, 25, housekeeper, b. Montgomeryshire, Darowen
John Edwards, son, unm, 23, leadminer, b. -do-
David Edwards, grandson, 4, b. -do-
Owen Owens, boarder, 50, engine driver at mines, b. Cardigan, ??
Gadget