Thank you for posting the family documents of my 3rd great-parents, Samuel Martin and Frances Eleanor Williams which has been of great interest. My guess is that the records arrived in Belfast through a descendant, Captain A.S. Dunlop R.A. of Holywood, Co Down. Who knows where the family bible went.
A dead end in my research are ancestors of the linen draper Robert Potts of Quarterland, Dundrod born about 1780 and died 1811. He was married to Sarah McCulloch, born 1787 and died 1860, and their sons were Ironmongers in North Street, Belfast. Another loose end are the ancestors of Eliza Jane McClean of Belfast born 1801 and died in 1861. She married Pooley Shuldham Henry of Antrim, born 1801 and died 1881. Thanks for the informative site.