Hi
Are you still researching the PRYTHERCH of Llanfairarybryn.
I am researching Rees Price SHUTT, he appears on the 1841 & 1851 census living at Parkwern, Llanfairarybryn with the PRYTHERCH family, sister Anne. His twin (presumably) brother Frederick is in the 41 census but not in the 51 census.
Strangely Rees and Elizabeth PRYTHERCH who are in the 1841 census appear to have changed names to Rees and Elizabeth WILLIAMS (their ages both fit) in the 1851 census.
In the 1861 census, Mary PRICE, William PRYTHERCH and Anne SHUTT are living in Garden Street, Llandovery, with Ann shown as Mary PRICE's daughter - which suggests that Mary is also the mother of Rees Price SHUTT. Interestingly there is a Mary PRICE in the 1851 Llanfairarybryn census, around the correct age, who is working as a servant for Rees PRICE. Could there be a link between Rees PRICE & Rees Price SHUTT?
In the 1871 census William PRYTHERCH is given as the father of Mary PRICE.
There is another SCHUTT family living in Bronfelin, Llanfairarybryn at the time of the 1841 census who have a brood of children around the same ages as Rees & Anne SHUTT - they are all related - but I don't know how?
I don't know if this has any links to the PRYTHERCH's you were searching!!