Williams Family Tree

Cannot find in Merthyr Tydfil in 1881, despite looking hard.

It's possible that William Williams, father of JTW, is this chap:
1861:
Name: William Williams
Age: 33
Estimated Birth Year: abt 1828
Relation: Son
Mother's name: Ealeanor Williams
Gender: Male
Where born: Ystradfellte, Breconshire, Wales
Civil Parish or Township: Vaynor
County/Island: Breconshire
Country: Wales
Street Address: View image
Condition as to marriage: View image
Education: View image
Employment status: View image
Occupation: View image
Registration district: Merthyr Tydfil
Sub-registration district: Upper Merthyr Tydfil
ED, institution, or vessel: 32
Household schedule number: 67
Neighbors: View others on page
Piece: 4062
Folio: 23
Page Number: 11
Household Members:
Name Age
Ealeanor Williams 70
Margaret Williams 35
William Williams 33
Thomas Williams 30

1851 Wales Census about William Williams
Name: William Williams
Age: 25
Estimated Birth Year: abt 1826
Relation: Son
Mother's name: Eleanor Williams
Gender: Male
Where born: Ystradfellte, Breconshire, Wales
Civil Parish or Township: Vaynor
County/Island: Breconshire
Country: Wales
Registration district: Merthyr Tydfil
Sub-registration district: Upper Merthyr Tydfil
ED, institution, or vessel: 2c
Piece: 2459
Folio: 756
Page Number: 26
Household schedule number: 110
Household Members:
Name Age
Eleanor Williams 60
Margaret Williams 29
William Williams 25
Thomas Williams 23
Elizabeth Williams 20

Both of the above are in Cefn High Street.
And it's possible that this 1881 census entry shows his family:
1881 census transcription details for: *163 High Street, Vainor (Brecon)*
*National Archive Reference:* *RG number:* RG11 *Piece:* 5318 *Folio:* 75 *Page:* 10 *Reg. District:* Merthyr Tydfil
*Sub District:* Upper Merthyr Tydfil *Enum. District:* *Ecclesiastical District:* *Parish:* Vainor (Brecon) *City/Municipal Borough:*

*Address:* 163 High Street, Vainor (Brecon) *County:* Glamorganshire
*Name* *Relation* *Condition* *Sex* *Age* *Birth Year* *Occupation,Disability * *Where Born*
EDWARDS, John Head Married M 46 1835 Iron Puddler Llandovery Carmarthenshire Wales
EDWARDS, Margt Wife Married F 58 1823 Ystradfellte Glamorganshire Wales
WILLIAMS, Thos Lodger Married M 53 1828 Ashfiller (Iron) Ystradfellte Glamorganshire Wales
WILLIAMS, William Nephew Single M 16 1865 B/smiths Striker Merthyr Glamorganshire Wales
WILLIAMS, Thomas Nephew Single M 13 1868 Scholar Merthyr Glamorganshire Wales
WILLIAMS, John Nephew Single M 11 1870 Scholar Merthyr Glamorganshire

And it's possible that the Margaret Evans with whom the family above is lodging is actually William's sister, with this marriage to John Edwards:

Surname First name(s) District Vol Page
Marriages Dec 1865 (>99%)
Edwards John Merthyr T 11a 606
Griffiths Sarah Jane Merthyr T 11a 606
Williams Margaret Merthyr T 11a 606
Wolsey Robert Merthyr T 11a 606

But everything seems to have disappeared in 1871! Can't find William or Thomas or Margaret Williams or margaret Evans!

On the FindMyPast free weekend, I looked for baptism records in Ystradfellte for all this family, but the records were missing. They did have the Ystradfellte burial records.