I searched the Irish Family History online database at ROOTSIRELAND.IE. It has abt 20M B/M/D records for most Irish counties. Records before 1863 are increasingly sparse: almost non-existant before 1800. Protestant records are the least likely to have survived.
For James and David Sanderson B 1830 +/- 5 yrs, Co. Donegal, with the parents' names unknown, I found 0 records.
Suggest you visit this database, register (free), and opt (also free) to be notified as additions are made to the database. It may be several years before all the original records are transcribed.