Perhaps a clue lies in the 1871 census,but before that Margaret Morris appears to have had a number of illegitimate children(?)
1851 census she has a son William(1842) and daughter Jane Kemp(?)(1848)
1861 census a daughter Margaret(1859
The 1871 census has her as head of household,alone in one major database,but on the next page immediately there is Robert James,described as son and Jane as wife,together with a William James also son.Jane's age is indecipherable/crossed out and William is given as 1849,but what if Robert James is her "son in law"with Jane his "wife",her dasughter and William her son misnamed as a James? - RG10/5570/56/23
I have put inverted commas to fit the next speculation.Elizabeth who appears as the granddaughter to Elizabeth Morris could be the daughter of Jane and Robert James(unmarried?).There is a death of a Jane Morris aged 30 in 1876 in the Tregaron district that could be the Jane above leaving Robert James to marry an Elizabeth.
Highly speculative,but worth consideration?
Regards
Roger