Looked up Clowning, a townland in Griffith Valuations in two parish's Greatconnell or Whitechurch, both in the Poor Law Union/Civil Registration District +1864. Also Newbridge was a town in 1853 not a Parish in the following Parish's Great Connell, Morristownbiller and Parish Kildare. Nass is the Poor Law Union/Civil Registration District and would cover a 12 mi. area.
I wonder if Christopher's death certificate shows his mother, whereas the other children were Brigid Flood's children.
I agree 2 Christophers may mean what you suggest, as that was common practice in Ireland. Perhaps Bridget died with the first named Christopher. There is the gap between 1843 & 1847 which might also indicate a new wife. And usually children every 2 years minimum in those days.
I've looked at Griffith Valuation's 1853 and find 19 William Kelly's, none in any of the parish's mentioned.www.askaboutireland.ie
3 Dennel's and 50 Dillon's.
Where does Newbridge come in? For example there was a Poor Law Union in Wicklow named Newbridge under British occupation, later its name was changed and now the only Newbridge is the town in Kildare.
Kildare County has parish records on an Irish History Foundation, it is a pay website but it would sort out your Christopher's. You have both names of parents and it will give you all the children they had. You can do the same but with the mother of the 2nd. Christopher. I look at the website and found none of the parish's as named in Griffith
Valuation with the exception of Kildare/Rathangan.
So there is a Kildare Parish that didn't exist in 1853.
Parish's were subject to amalgamation, division and closure due to the Diocese and church needs. www.rootsireland.ie
This parish notes no formal registers from 1837-1849, other than that (note includes your family) go from 1815-1899.
I think someone must of made a mistake on the birth and the christening dates. It makes sense that way as RC baptised as soon as possible after birth and often in the mother's, mothers church as mum's went home for childbirth. Church of Ireland can be longer but generally the first Sunday after birth. Depending on circumstances you can see children baptised a year later.
I do know that Rathangan has records on line, I don't know if they are still there but I do remember AtoZmarriages.
I'll see if I can find it, haven't looked for 5 years+.www.atozmarriages.com/ireland/kildarewww.kildare.ie/library/slater's
William Kelly's: 1881
1)ironmonger & hardwareman
2)grocer & spirit dealer
3)coal and timber dealer
There are Christopher's of the right age, and one the right area age 52, New Road, Naas Urban. 1 William perhaps old enough that isn't a farmer? There is 1 only Elizabeth Kelly age 68.
There are just too many Kelly's in the Kildare telephone book to make any connections.
Hope that is of some assistance to you.