With the exception of the 1881 census, James Griffiths age leads to a birth around 1815, and most give a birthplace of Trostrey.
Luckily, there were very few Griffiths in the Trostrey church records. I may have missed some:
Trostrey
1810 Marriage of James Griffiths to Mary Jones. (Some indices say Mary James. It is without a doubt written as Jones)
1811 baptism of Mary dau of James Grifths [sic] and Mary
1814 baptism of James of James and Mary Griffiths Trostrey Common, labourer
1818 baptism of Elizabeth to James labourer in husbandry
1820 baptism of John of James and Mary Griffiths labourer in husbandry
1824 baptism of Anne of James and Mary Griffiths Trostrey Com
SAWYER1837 baptism of William born to single Mary Griffiths
Trostery burials
James Griffiths age 84 Trostrey Common 16 May 1867 (b 1783)
Caroline Griffiths 03 Jun 1894 age 79 Trostrey Common (need to see if that could be the one from the potential marriage to youngest James)
Ann Griffiths 1838 08 May Trostrey age 14 yrs 8 mo (matches James and Mary's daughters age)
Mary, mentioned 3 lines down:
James Senior and Mary appear on the 1851 census still in Trostrey.
James Sr is widowed on the 1861 census.
There is a possible burial for Mary: Mary Griffiths age 67 (b 1785ish) 30 Jan 1852 Trostry
The daughter Mary married James Hobbins in 1844 in Trevethin, of full age, father James Griffiths, sawyer
There is a possible death registered for each of them in 1879. They are with James and Mary Griffiths on the 1861 census.
The son John Griffiths married Mary Ann Williams in 1845, and was living in Trevethin at that time. His father is given as James Griffiths, sawyer.
Most censuses he is an ag labourer, but on the 1851 he is a sawyer:
John Griffiths, Head, age 28 Sawyer b Trostrey
Mary Ann wife age 24 b Gwehellog
Mary Ann dau age 2 born Usk
Elizabeth dau age 2 months born Usk
Elizabeth Williams niece age 7 b Abersychan
Esther William mother in law widow age 52 born Gwehellog
Note that the Williams family we are interested in is also from Gwehellog.
James Griffiths born 1814 (the one we think is Emily's father); on the
1841 1851 he is widowed, with a 13 yr old son James, and a 7 yr old daughter Sarah. I can't nail either of these down. I wanted to track Sarah, as we have the Sarah Williams that "should" be his as well?
In Reply #5, Osprey noted this:
Possible marriage 1 March 1852 parish church of Trevethin for James Griffiths sawyer & Caroline Richards, his father James also a sawyer. But he is noted as a bachelor.That may very well be the 13 yr old James in the 1841. It was the 1851, so too young.Jumping back to James Sr, in the 1861 census, he has some relatives visiting him. A James Albins, age 50, b Rhadnorshire, and also a Mary Albins, b Monmouthshire. Mary does not show in the index, only the image. Given that she is the one from Mons, I would think she was the relative.
On the 1851, James Sr says he is born Newgate, Gloucestershire, but the 1861 states Trostrey.
Sorry this is rambly, but the old laptop is getting too hot and didn't want to lose my notes!
Some of this might help sort the family out a bit, but still doesn't help us with Emily
Edited in red to correct a senior moment when I mixed up the 1841 for the 1851 census. Apologies!