Fermanagh Co. is a difficult place to search as there are great gaps in information. I looked to Clogher Diocese for the marriage you list of Andrew and
Isabella Coulter 1806.
It is possible that Isabella's last name was incorrectly recorded/transcribed, however, it wasn't unusual for cousin to marry cousins. Andrew is an unusual name for the time, as is
Isabella. Two different data bases for bmd show two different amounts of records they each have. One show 774 Births for
Coulter. First is 1111 then nothing to 1823+. The other shows records from 1864 the time of civil registration, no records of
Isabella till 1872, which we know isn't her but perhaps a family name.
A check of
Griffiths Valuations a good census substitute for finding surnames and Parishes record 70 Coulter's in 1862 in Fermanagh. Diocese could easily cover several counties as the later Civil Registrations from 1864 could include more than 1 county. (see Griffith's websites below)
www.from-ireland.net for descriptions of different division for
Irish records, Diocese, County,
Parish, Townlands, Poor Law Unions, Civil Registrations.
www.censusfinder.com United Kingdom+Ireland+County Excellent Fermanagh website:
has early census and parish records, tithes for 1824-35.
Just one
Parish Derryvullan had 9 Coulter's, George, James, John, William 4 different Townlands.
www.failteromhat.com has Griffith's Valuation (also directories 1824, 1846 but no Coulters) for 1862 for Fermanagh which is late but will show how many Parishes Coulter's lived in. Which is important for finding parish records, most records need to be searched in person unless you can find someone who has done them already, you will need to know if Protestant or Catholic as each has different storage of records and ways of finding the
Parish records. The
Griffith Valuations is also available on
www.askaboutireland.com with land descriptions.
Alexander
Coulter, Magheraculmoney
Parish, Drumhoney TL
Andrew x 2, Magheraculmoney, Ballydoolah, Townland
Andrew, Enniskillen, Brockagh Townland
Andrew, Enniskillen,
Carrow Nagitagh townland
These are the only uses of both names I would go with the assumption they are family names handed down through generations. If I visited Ireland or in using a genealogist those are the Parishes I would start a search.
Other websites you might try for history and to find more about Fermanagh would be
www.ulsterancestry.com and the Diocese of Clogher as it is possible you may never be able to find the records to find family. There are still a lot of Coulter's living in Enniskillen, Fermanagh by a check of the white pages
www.thephonebook.bt.com (British Telephone for Northern Ireland)
www.familysearch.org - use search with Ireland as place this is where I did find an
Isabella Coulter in the 1880 US Census, for information only.
1880
Isabella Coulter, born 1811 (is too young for your
Isabella) She was also in the 1870 Census her son was born in New
Brunswick, Canada.
In the
PILOT program for familysearch the LDS website had a
Isabella Coulter who died in Ontario on April 6, 1884 born in Fermanagh. There were only a few
Coulter records none that would apply to your
Isabella who would of been born around 1786 (best guess)
Gravestone inscriptions maybe your best bet for records if you can find the right
Parish