Have you seen
http://www.irishgenealogyhub.com/down/tithe-applotment-books/kilkeel-parish.php#.VSV2JkuDoYU There is a possibility that Shaw Agnew of Kilkeel might be a son of one of these Agnew listed as householders land was at least one acre
Agnew, George Townland: Glenloughan Year: 1830
Agnew, James Townland: Ballinran Year: 1830
Agnew, James Townland: Ballymaderphy Year: 1830
Agnew, James Townland: Moneydaraghmore Year: 1830
Agnew, John Townland: Glenloughan Year: 1830
Aiken, John Townland: Magheramurphy Year: 1830
Aiken, Robert Townland: Magheramurphy Year: 1830
Looking for Shaw, just produced
Russell, Shaw Townland: Moneydaraghmore Year: 1830
The Newalls include
Newall, Alexander Townland: Moneydaraghmore Year: 1830
Newall, Archibald Townland: Ballykeel Year: 1830
Newall, David Townland: Ballykeel Year: 1830
Newall, Francis Townland: Aughiochal Year: 1830
Newall, James Townland: Ballykeel Year: 1830
Newall, James Townland: Ballymaderphy Year: 1830
Newall, James Townland: Lisnacree Year: 1830
Newall, John Townland: Ballykeel Year: 1830
Newall, John Townland: Drummond Year: 1830
Newall, John Townland: Drummondoney Year: 1830
Newall, Richard Townland: Glassdrummond Year: 1830
Newall, Robert Townland: Glassdrummond Year: 1830
Newall, Widow Betty Jane Townland: Ballykeel Year: 1830
Newall, Widow Jane Townland: Ballykeel Year: 1830
Newall, William Townland: Aughiochal Year: 1830
Newall, William Townland: Ballykeel Year: 1830 Notes: Bank
Newall, William Townland: Drummond Year: 1830
Newall, William Townland: Glassdrummond Year: 1830
Newall, William, Jr. Townland: Ballykeel Year: 1830
Newall, William, Sr. Townland: Ballykeel Year: 1830
Griffiths valuation comes with the primary valuation done in 1863 if you want more than index entries you need
http://www.askaboutireland.ie/griffith-valuation/ which reproduces the book entry and has maps!! Showing homesteads then thereafter the PRONI extends the valuation and will cover up to about 1921, it should show who took over Shaws homestead at the time of his death .
My broadband is acting up tonight but I am used to getting more clues from clumps of family name as you have surrounding Shaw who must be relatives in 1863.
In the 1901 census you have 33 Agnews living in the DED Mullarton including a John
Agnew John 94 Male Head of Family Presbyterian County Down Farmer Read - Widower living with sons and daughters at 21 in Moneydorraghmore Upper (Mullarton, Down) also several Elizabeths one of whom could be the widow of Shaw?
So I am closing down, hope some of this moves you on abit JimG
ancestryireland was where Iwas going to look for the marriage