Hi,
I am descended from Jane, Thomas and Rachel's child. She later lived at Penycerrig farm with her husband, Daniel Jones. They then ran the Grey Cow Inn, John Street, Carmarthen. Like yourself I have no other information. I have seen on the ancestry site that several people have said that John Richards, and Jane Davies were his parents, although I have seen no evidence of this.
I don't live far from that area, so I may visit some of the chapel cemetries that you have not.
Thanks