I found the locations mentioned difficult to put into perspective
eg
I started with Ros Davies Co Down website
http://freepages.genealogy.rootsweb.ancestry.com/~rosdavies/with an entry
James MORRISON . Hillsborough of Ednacullo; died 1 Mar 1879; will probated 1882 EA/Wills ie as noted by
I found no connections with Drumlough which could be in Dromore or Drumgath parish. I went down the Dromore path. Ros Davies gives
John CAIRNS . Dromore husband of Catherin McDowell ; father of William John b. 7 Mar 1837 & Margaret Jane b. 10 May 1838 & bpt. Dromore church of Ireland PR
Miss Margaret KEARNS/ CAIRNS . Knockbreda regd. Castlereagh; wife of Anthony Morrison; mother of Margaret b. 1865 & Anna Maria b. 1869 CR
Anthony MORRISON .[??m 1846 reg Hillsborough] Knockbredaregd. Ballymacarrett; husband of Margaret Kearns / Cairns ; father of Margaret b. 12 Apr 1865 & Anna Maria b. 30 Mar 1869 CR
emeraldancestors.com gives James Morrison m
a Margaret in 1857 ballymoney
a Margaret in 1859 lurgan
a Margaret in 1861 lisburn
a Margaret in 1862 more other places
I think Lisburn could have been a regional registration district so could cover Hillsborough or further afield.
then I remembered answering Cairns:Drumlough birth lookup on
http://www.rootschat.com/forum/index.php?topic=732528.msg5776257#msg5776257I think I stop now sorry I cant help more