1. Couldn't find any Owen Williams living at Llechfraith or Uwchmynydd. There were three in Meirioneth, two had wives, neither were called Ellin.
One was born 1795 Llanfrothen and lived in Llanfrothen.
The second was born 1799 in Llanbedr and lived at Maentwrog
The third was widowed, born 1797 in Maentwrog and lived at Llangower, Uwchafon, by Bala lake.
2. There are two Owen Williams with birthplace noted as Llandanwg which is about 5 miles north of Llanddwywe. The same household seems to have been counted twice under two different census returns!? The details are the same on both.
Tyddyn Du, Llanfair Parish, Llanenddwyn, Meirionethshire
also (no address) Llanfihangely traethau, Llanfair, Meirionethshire
Name Birth Birth Place
John Griffith abt 1817 Llanfair, Merionethshire Head Farmer of 100 acres
Margaret Griffith abt 1820 Celynia, Merionethshire Wife
Jane Griffith abt 1852 Llanfair, Merionethshire Daughter
Ellis Griffith abt 1808 Celynia, Merionethshire Brother-in-law
Ellen Richards abt 1842 Llandecwyn, Merioneth. House Servant
Richard Richards abt 1844 Llandecwyn, Merioneth. Servant - Ag Lab
Jane Williams abt 1839 Llandanwg, Merionethshire Servant - Ag Lab
Owen Williams abt 1843 Llandanwg, Merionethshire Servant - Ag Lab
Hope this helps!
Tan