Any idea how old they were at the time of death?
These are the entries for the whole of Offaly in GV from
http://www.failteromhat.com/Kilmartin John Endrim Killaghally or Wheery Offaly
Kilmartin Keiran Creggan Killaghally or Wheery Offaly
Kilmartin James Endrim Killaghally or Wheery Offaly
Kilmartin Michael Dromoyle Kilcolman Offaly
Kilmartin William Lisheen Eglish Offaly
Kilmartin Daniel Derrydolney Killoughy Offaly
Kilmartin Michael Derrydolney Killoughy Offaly
Kilmartin Daniel Gorteen Roscrea Offaly
Kilmartin James Lismoney Kinnitty Offaly
Kilmartin James Town of Kinnitty,Ballincur Kinnitty Offaly
Kilmartin James Ballincur Kinnitty Offaly
Kilmartin John Coolnahinch Gallen Offaly
Kilmartin John Clyduff Dunkerrin Offaly
Kilmartin William Castle Street,(Townparks) Barr Offaly
Kilmartin Patrick Ford Kyleboher Ballyboy Offaly
Kilmartin Patrick Ford (Part of) Main Street Ballyboy Offaly
Kilmartin John Ballynacarrig Ballyboy Offaly
Kilmartin Edward Clonmacnoise Clonmacnoise Offaly
Kilmartin James Clonmacnoise Clonmacnoise Offaly
Kilmartin James Annaghmore and Annaghbeg Drumcullen Offaly
Kilmartin Catherine Knockbarron Drumcullen Offaly
Kilmartin Michael Clonmacnoise Clonmacnoise Offaly
Kilmartin John Creevagh Clonmacnoise Offaly
Kilmartin John Ballincloghan Ballyboy Offaly
You will see a Daniel in Derrydonley.
Also a Michael. The descendant of this Michael I think shows up on the 1901/11 census.
http://www.census.nationalarchives.ie/Take a look there especially at the older ones - don't ignore the women as some may be unmarried sisters and not widows
Then I searched on this site.
http://www.askaboutireland.ie/You can get all sorts of detail about the holdings......they may lease land in other townlands but not occupy the house and grounds. By looking across all the entries you can see where they might have lived.
Coolreagh is in Cloghan and is some times called Cloganhill.
When looking at records for people in Kings I also look in Tipperary records as some people on the borders gravitated to towns in Tipperary to register their especially if these were the towns they went to for market days etc. So do same searches on GV for Tipperary. north Riding of Tipperary also included parts near Roscrea near the Kings townlands.
It is a good idea to have a townlands map open when you do these searches.