Ahh, nevermind
I have since merged the 2 threads together (to alleviate any confusion)
Going through the print out from the information you gave yesterday.
The placenames giving you confusion are:
Adderanon = Aberafan
Pontrhydyfe = Pontrhydyfen
The Census information for 1901 1891 & 1881 seem to be the correct Heycock family. It is just a question of now finding out about the census futher back , will have another look through the 1841 - 51 & 61 Glamorgan census' for you to see if i can fathom it all out!
Hopefully some one can give you an 1871 Glamorgan look up for the family concerned
The 1861 census detail I gave you is the only possible for John c. 1843 So I believe this is the correct entry for him, which would mean he is not married in 1861:
Glamorgan Family History Society 1861 Census CD
083 1861 CENSUS OF MICHAELSTON LOWER. R.G.9/4083, E.D.16.
Piece: 4083 Folio: 072 Schedule: 207
Address: YNYS DAVID
HEYCOCK JOHN HD M 51 COLLIERY OVERMAN
GLA MARGAM (c1810)
HEYCOCK ELIZABETH WI M 48 -
GLA MARGAM (c1813)
HEYCOCK ELIZABETH DA - 23 DRESSMAKER
GLA MARGAM (c1838)
HEYCOCK MARY DA - 21 HOUSEMAID
GLA MARGAM (c1840)
HEYCOCK JOHN SO - 19 COAL MINER
GLA MARGAM (c1842)
HEYCOCK SAMUEL SO - 17 COAL MINER
GLA MARGAM (c1844)
HEYCOCK ANN DA - 14 HOUSEMAID
GLA MARGAM (c1847)
HEYCOCK BETHUEL SO - 10 SCHOLAR
GLA MICHAELSTON-SUPER-AVON (c1851)
HEYCOCK REES SO - 6 - [
GLA MICHAELSTON-SUPER-AVON] (c1855)
HEYCOCK WILLIAM SO - 4 -
GLA MICHAELSTON-SUPER-AVON (c1857)
HEYCOCK ELIZABETH DA - 5M -
GLA MICHAELSTON-SUPER-AVON (c1860)
The other Heycock's who I think could possibly be related ( I have a feeling the two heads of the households x2John's are cousins or perhaps Father & Son?) are below, note there is a Baby 2mths old, and the husband and wife are John & Elizabeth also. I think this is where you have gone wrong perhaps?:
Glamorgan Family History Society 1861 Census CD
4080 1861 CENSUS OF HAFOD-Y-PORTH. R.G.9/4080, E.D.4.
Piece: 4080 Folio: 093 Schedule: 176
Address: HIGH ST.TAIBACH
HEYCOCK JOHN HD M 32 COAL MINER
GLA MARGAM (c1829)
HEYCOCK ELIZABETH WI M 22 -
CMN LLANELLI (c1839)
HEYCOCK CATHERINE DA - 8 SCHOLAR
GLA MARGAM (c1853)
HEYCOCK MARY A. DA - 5 SCHOLAR
GLA MARGAM (c1856)
HEYCOCK JOHN SO - 2M -
GLA MARGAM (c1861)
REES THOMAS BO M 60 LABOURER
CGN LLANGYNLLO (c1801)
EVANS JOHN BO U 19 COAL MINER
GLA LLANGYNWYD (c1842)
It could be that this couple were the ones getting married Sept quarter of 1859 in Neath. The older children may be born out of wedlock or Elizabeth (possibly Rees) may be their step mother. The census would note the head of the households relationship to the rest of the family listed.