« Reply #24 on: Saturday 31 October 20 18:36 GMT (UK) »
going back to the 1851 census in Merthyr Tydfil, John & Maria are visitors in the household of James & Esther Ol(l)iver.
Birth regs for children
Joseph Oliver sept qtr 1847 Merthyr Tydfil vol 26 pg 401 mmn Austin
Thomas Oliver sept qtr 1850 Merthyr Tydfil vol 26 pg 463 mmn Austin
marriage ref
James Oliver dec qtr 1843 Presteigne vol 26 pg 397 with Hester Austin the only other name on the page.
1861 census, place of birth for Esther & George looks like Windfordon
https://www.familysearch.org/ark:/61903/1:1:M717-6H8So it's possible that John was visiting his sister.
Cornwall: Allen, Bevan, Bosisto, Carnpezzack, Donithorn, Huddy, James, Retallack, Russell, Vincent, Yeoman
Cards: Thomas (Llanbadarn Fawr)
Glam: Bowler, Cram, Galloway, James, Thomas, Watkins
Lincs: Coupland, Cram
Mon: Cram, Gwyn, John, Philpot, Smart, Watkins
Pembs: Edwards (St. Dogmael's)
Yorks: Airey, Bowler, Elliott, Hare, Hewitt, Kellett, Kemp, Stephenson, Tebb