Shillady.

[hallmark]

A Search like this on

https://civilrecords.irishgenealogy.ie/churchrecords/civil-search.jsp

will get any BDM Registrations for them up to 1922

Change Surname if one wants.

[hallmark]

The Irish Government BDM website

https://civilrecords.irishgenealogy.ie/churchrecords/civil-search.jsp

has 3 stages to it as per attachment
 

Those with Returns Page No  don't have Images yet but one can check back every now and then to see if any have been updated even once every 6 months!


If one knows the names from a Marriage e.g.  "about 1870"  just put Name in, Tick Marriage box and use Year Range 1868 to 1872  leaving District  blank if unknown!

The Captcha and Sign in page are all part of process the Irish Government BDM website and do not take anyone to any other website!

[Cwellan CoDown]

There is a hardware shop in Castlewellan called Shillidays and it's been there since 1926

As far as I know the owner isn't young - so might be able to help you out

[BallyaltikilliganG]

Also check the sources now on line  eg
1796 Flax growers of Ireland none found

1823-1837 Tithes Applotment Books based upon the index work of the Irish Genealogy Hub’s listing for each parish in Northern Ireland, which are quicker to lookup if you know the parish!
The relevant original books are in the Public Record Office of Northern Ireland (PRONI) Belfast If in bold its a neighbour civil parish.
Shilady, Joseph   Townland: Darkley Year: 1825   Keady      Armagh
Shillady, Thomas   Townland: Darkley Year: 1825   Keady      Armagh
Shillady, Widow   Townland: Ballykine Year: 1826   Dromara    Down
Shillady, Widow    Townland: Ballykine Year: 1828   Dromara    Down
Shillady, John      Townland: Skillyscolban Year: 1834   Dromore   Down
Shilladay, Hugh   Townland: Ballyhaffry Year: 1829   Kilcoo      Down
Shilliday, John   Townland: Ballymoney Year: 1829   Kilcoo      Down
Shilladay, Hugh   Townland: Tullinasough Year: 1829   Kilcoo      Down
Shilladay, Jn.      Townland: Tullinasough Year: 1829   Kilcoo      Down
Shilliday, James   Townland: Drumcaw Year: 1828   Loughinisland    Down
Shilliday, John   Townland: Carnacavel Year: 1831   Maghera   Down
Shilliday, John   Townland: Kilmacrew Year: 1833   Magherally   Down  1863

Griffiths valuation three sources
1. https://www.failteromhat.com for quick index. 
2. http://www.askaboutireland.ie/griffith-valuation/ for detail and map ref .. 
3. https://www.nidirect.gov.uk/information-and-services/search-archives-online/valuation-revision-books since item 2

[akanex2]

Be aware I have found Co Down Shilladays also using the surname Sheridan!

[BallyaltikilliganG]

akanex2, i had a quick peek at Sheridan thus to get an overview of the spread of the name compared to Shilliday in Co Down

KIlmore to Drumballyroney isover 20 miles
1796 Flax growers  see https://www.failteromhat.com/flax/down.php
Sheridan          John                 Kilmore                         Down
Sheridan          Owen                 Kilmore                         Down
Sheridan          Silvester            Kilmore                         Down
Shilliday         John                 Drumballyroney                  Down
Shirnon           Thomas               Kilmegan                        Down
Shoridan          Thomas               Kilmore                         Down

 tithes in co down
Sheraton, John-Townland: Lisnaree Year: 1828-Seapatrick-Down
Sheridan, James-Townland: Fofany Bawn Year: 1829-Kilcoo-Down
Sheridan, Pat.-Townland: Ballywillwill Year: 1829-Killmegan-Down
 
griffiths
Sheridan   John   Abbey Yard,Newry   Newry   Down
Sheridan   Thomas   High Street,Newry   Newry   Down
Sheridan   John   Ballynacraig   Newry   Down
Sheridan   Patrick   Fofannybane   Kilcoo   Down
Sheridan   John   Bridge Street,Downpatrick   Down   Down
Sheridan   Thomas   Ballyrussell   Clonallan   Down
Shilliday   Robert   Moneygore   Drumballyroney   Down
Shilliday   John   Ballykine Lower   Magheradrool   Down
Shilliday   John   Ballykine   Magherahamlet   Down
Shilliday   John   Moneygore   Drumballyroney   Down
Shilliday   James   Drumarkin   Drumballyroney   Down
Shilliday   James   Ballymaghery   Clonduff   Down
Shilliday   James   Hilltown,Carcullion   Clonduff   Down
Shilliday   James   Cavan   Drumballyroney   Down
Shilliday   Elizabeth   Drumnascamph   Clonduff   Down
felt no connection, yet you have examples