I think I have good news for you, on both the marriage and birth enquiries you recently posted! I have a copy of the marriage certificate of Daniel Davies and Mary Evans, married 20th October 1877.
Daniel Davies 19 years Batchelor Coalminer Cwmpandy Nr Neath Father: Samuel Davies deceased
Mary Evans 20 years Spinster Mount Pleasant Neath Father: David Evans
I tried to scan the cert for you, but haven't yet found how to do this! Also you asked about Daniel and his birth records at LLangynwyd, Maesteg. I'm not surprised you couldn't find this as it caused me many sleepless nights - he was actually born in Carmarthen. Because he was recorded on 1871, 1881, 1901 census as born in Maesteg, it was only when I discovered his stepfather was from Maesteg that the whole family was listed as being born there, but in fact his mother and family were from Carmarthen.
There is much more info on the family if you would like it so please let me know.
Regards,
Chris