Hi Jan,
My apologies for missing your earlier post - I've been distracted by other matters of late !
I do not have your Catherine Gethin (b.1813) in my tree. Edward & Catherine Gethin did have a daughter Catherine, born 1799, but she died in 1810. They then went on to have Jane (b.ca. 1802) and Richard (b.ca.1803), who married Mary Tudor, all born in Tregynon. Now the probability is that there were more than 3 children, quite a small family in those days, and there may well have been another Catherine born after No.1 died in 1810. Speculative, I know, but worth a proper look in the parish records of Tregynon, if you have the opportunity.
Re: Martha Tudor. Yes, there is a Martha, b. 1768 Tregynon, a sister to John Tudor (b.1765), the father of Mary Tudor (b. 1806, Llanwnog), who married Richard Gethin. i.e. Aunty Martha ! It appears that Martha married John Richards,a widower, on 31 Dec 1801. She would have been about 33 years old. Probably, the right one.
Martha & John are 2 of the 9 children (at least!) of John Tudor & Bridget (no surname). If you need any more details, please let me know (most of the information has come from a website, therefore not guaranteed).
Regards
Stan
