I think it is Llandybie, which is just north of Ammanford
Think this may be the family in 1891,
RG12/4451 ED4 folio 104 page 63
3 Dinaur St., Ynsawdre, Llandyfodwg, Glamorgan
William Merriman head m 46 milk seller Carm. Hendygwyn Welsh
John “ son s 20 underground haulier Glam. Cwmaron Welsh
James “ son 14 milk seller Glam. Treorchy Welsh
William “ son 11 Glam Pontypridd Welsh
William J “ son 3 Glam. Nant y moel Welsh
Margaret Phillips daur m 23 general servant domestic Carm. Llanbydie Welsh
Mary Phillips daur 4 months Glam. Nant y moel
Think this is Rachel 1891:
RG12/4456 ed Glamorgan County Asylum folio 124 page 41
Rachel Merryman married 47 collier’s wife Carmarthen Landebie Lunatic Welsh
1871
RG10/5410 ed37 folio 123 page 43
Aberdare, Glamorgan
William Merryman head m 26 coal miner Carm. Cyffyg
Rachel “ wife m 27 Carm. Llandebie
Margaret “ daur 3 Carm. Llandebie
John “ son 11 months Glam. Aberdare
Thomas Richard lodger un 24 coal miner Carm. Llandebie
David Davies lodger un 20 coal miner Carm. Llandebie
Hohn Thomas londer un 18 coal miner Carm. Llandebie
Mary morris lodger un 21 washer woman Carm. Llannon
Thomas Richard (lodger above) may be Rachel’s brother
Marriage Dec 1866 Merthy T. 11a page 528
William Merriman Rachel Richards
1851 HO107/2471 ED3f folio 663 page 25 has a Rachel Richard aged 6 and a Thomas aged 4.
Hope this helps
(sorry some of it is duplicates of what is already posted, obviously we were working on it at the same time!)
regards