Noswaith dda!
The information I have is in the form of a booklet, and is a private census of all the houses in Dolwyddelan between 1838 and 1842, and lists not only the occupants, but also their ancestors, in-laws (and where they came from) and descendants! It then becomes so much easier to find official records!
Before I was given a copy of this, I had spent years trying to track my Taid's father's family, and one look at "Ffridd" and I realised I had been looking for Davies, when it was listed as "Dafydd", and later elsewhere as "Dafis" and again as "Davys"!! It also told me that the son, Owen, married his cousin Mary - and that explained resemblances on a couple of family photos! Marriage Certs and official census's don't always give an inclining of anything like that!
The sections for B. Bach and Penrhiw take up 3/4 of a page of A4 typing, and I just don't have the time to type it all out, but I am very happy to scan the relevant bits and email them to you, if you will send me a PM with your email address. Likewise for any other addresses which interest you!
Regards,
BM