Hi Laura,
Sadly, I have no further information. All I have to go on is my Grandmother's birth certificate. She was also a Margaret Rees(!) and was born in Welcome Street, Morriston, Swansea on the 6th November 1866. The informant on her certificate is her mother, Margaret Rees, (maiden name Rees!). She is unable to sign her name on the certificate, but has made a cross instead.
She married my Grandfather, Evan Rees, (a Copperman) presumably in about 1858, because her eldest son, John was born in Aberavon in 1859. Margaret Rees, (Senior) was also born in Aberavon, but Evan Rees was born in Morriston in approx 1838.
I have found my Great Grandparents on the 1861/71/81 and 1891 Censuses for Wales. I've also found Evan Rees's parents, (Evan and Anne Rees) but have been unable to find anything further for my Aberavon Margaret Rees. I don't know if she was any relation to the Evan Rees that she married. The children's names of Evan & Margaret Rees might give some clues, they were: John (1859) Sarah Ann (1862) Margaret (1866) George (1868) Elizabeth (1872) Selina (1877) and William (1879).
I've looked in vain for a birth entry for Margaret Rees, Snr, but suspect that she probably wasn't registered. On the Censuses, Margaret Snrs date of birth is given variously, as being 1837, 1838 and 1839!
Many thanks for looking, but as you say...I expect there were an awful lot of Rees's in that part of Wales!!!
Best Wishes, Romilly