Do you have the marriage certificate for Jonathan & Mary J Griffiths to confirm names & occupations of fathers? Without that info, it's just guessing. When & where was Mary J born?
Working back through the census years for the family of John Evan Jones and Ann gives 8 children -Thomas, Robert, Mary, Evan, Margaret Ann, Catherine, Hannah & Jonathan - no Gladys or Sarah. Checking the birth registrations shows mother's maiden of Davies
Jonathan Jones dec qtr 1888 Merthyr Tydfil vol 11a pg 506 mmn Davies. Several possible marriages with John Jones & Ann Davies on the same page before the birth of first child Thomas about 1869.
Several John Jones of around the right age born Llanfynydd which is given as his place of birth on one census. There's this possible in Merthyr Tydfil in 1851
Castle St, HO107/2458 folio 295 pg 4
Mary Jones head widow 46 householder b. Carms, Llanarthe
Thomas son 17 coal haulier b. Carms, Llanfynydd
David son 15 general labourer b. Llanfynydd
John son 7 at home b. Llanfynydd
red post, will continue...
