I search the IFHF's online database at ROOTSIRELAND.IE. It has abt 19 million B/M/D and other records for MOST Irish counties. Records before 1863 are increasingly sparse. They are almost non-existant before 1800. Many B/M/D events either weren't recorded, or haven't survived.
For the surname Develin/Devlin there are 12,819 B and 6,274 M records in this database. A google search for Killyblaught found NO matches. Either it isn't in the google database, or your info has become garbled in the last century. The closest match is Killbeg which is in Co. Donegal.
In Co. Donegal there are 781 B and 264 M records.
Visit this database when you have some estimated DOB/DOM and forenames, etc.