Heres a start on the irish sources
Ballymartin townland appears to be in two civil parishes Tullynakill and Kilkeel in Co down. There is a considerable distance between them and I think Tullynakill can be left out o your searches
Ros Davies Co Down website has more accurate dates
http://freepages.genealogy.rootsweb.ancestry.com/~rosdaviesPatrick SLOAN(E) . Kilkeel of Magherareagh then Leestone ; husband of Betty Sarah Walmsley; father of
Mary bpt. 24 Sep 1848 (sponsors were John Rooney & Mary McAlindon) &
Patrick bpt. 20 Jun 1852 (sp. Pat Rooney & Margaret Cunningham ) &
Catherine bpt. 13 May 1853 &
Hugh bpt. 14 May 1854 (sp. John Trimble & Mary Quinn) &
Christian bpt. 14 Apr 1856 (sp. Jamessley & Margaret Thompson)
all at at Lower Mourne Catholic Church PR
Notes Ros
has entries for Sloane of Kilkeel civil parish where there are S’ living back to early1700
has Betty Sally under the Walmsley heading and then of Kilkeel civil parish where there are W’s living back to early1700
Tithe-Applotment-Booksfrom
http://www.irishgenealogyhub.com/down/tithe-applotment-books/kilkeel-parish.php#.Vl7XCUvBEYUMcDowell, Alexr. Townland: Moneydaraghmore Year: 1830
McDowell, Robert Townland: Moneydaraghmore Year: 1830
Walmsley, George Townland: Ballymagart Year: 1830
numerous Sloane
http://www.irishgenealogyhub.com/down/tithe-applotment-books/tullynakill-parish.php#.Vl7YZUvBEYUfrom there are no McDowell Sloan{e} Walmsley
As the family is catholic I worried about my inclusivity to Kilkeel civil parish as it differs frim the Catholic parish of Kilkeel.the catholic parish name is and found the following explanation on
http://www.historyfromheadstones.com/index.php?displaygraveyardinfo&graveyard_name=Ballymartin Graveyard Name : Ballymartin RC Civil Parish : Kilkeel Town / Townland : Ballymartin OS Reference : J341165
Other Information : The church [
St Josephs Catholic Church Bamllymartin –Lower Mourne] is a conspicuous object on the inland side of the coast road about half way between Annalong and Kilkeel. Is In the townland of Ballymartin and civil parish of Kilkeel but in the Catholic parish of Lower Mourne, The old parish of Mourne was divided in 1768 and the parish priest of this half, the Rev James Killen, built a church at Ballymartin some time before 1790 when he died, The church was entirely rebuilt in 1825 The graveyard contains few ancient stones, the oldest dating from 1820 most are of rough granite and are difficult to read The graveyard lies entirely to the south of the church. Ros Davies adds in The graveyard is attached, gravestone inscriptions available UHF Vol 10, oldest stone 1820; email me for a gravestone look-up
The other church is
St. Mary's Catholic Church, Glassdrumman - Lower Mourneon the western side of the Newcastle to Kilkeel road
This chapel was built in 1832 ....Newspaper article from Northern Herald;
consecration 21 Dec 1833
{RECORDS} PRONI & NLI have baptisms 1842-1881 & marriages 1839-1880; UHF have baptisms 1842-1900 & marriages 1839-1900;graveyard nearby, gravestone inscriptions available UHF Vol 10; email me for a gravestone look-up
moving to
Griffiths Valuation http://www.failteromhat.com/post1845.phpMc Dowell James Moneydorragh More Upper Kilkeel Down
Mc Dowell John Moneydorragh More Kilkeel Down
Mc Dowell John Newry Street,Kilkeel Kilkeel Down
Mc Dowell Margaret Greencastle Street,Kilkeel Kilkeel Down
Mc Dowell Samuel Shore Road,Kilkeel Kilkeel Down
Sloan Mary Ballymartin Tullynakill Down
Sloane an amazing no of entries inc
Sloane Nicholas Ballymartin Kilkeel Down
Sloane William Ballymartin Kilkeel Down
Walmsley 14 including
Walmsley George Ballyardel Kilkeel Down
Walmsley George Ballymagart Kilkeel Down
The other website that has more detailed information as
www.askaboutireland.com then find Griffiths , it has maps about 1860 that can tell you much. Finally of you dont know the area google maps and enlarge ballymartin until you are in satellite and street scenes
Good luck with relatives JimG