You've already been to Ireland, but I hope you did further research on the Internet before your trip. The LDS-IGI includes microfilm of many years of the Clones church records. The original Clones parish Church of Ireland(St. Tighernach's, an absolutely beautiful church overlooking the Diamond in Clones) registers are now at the RCB Library in Dublin. The cemetery, sadly, suffered substantial damage on one side when a wall collapsed a few years ago from work being done on the residential property below it.
The Clones Church of Ireland marriage record below is on LDS microfilm (included on web site): "Extracted marriage record for locality listed in the record. The source records are usually arranged chronologically by the marriage date."
WILLIAM FERGUSON - MARGT WIGGINS Marriage Date:25 APR 1828 Location of record: Church of Ireland, Clones, Co. Monaghan, Ireland
I don't know their children's names but you might findbaptisms in the LDS-IGI as well, and other records such as deaths/burials.
You might find your ancestors' records not only in the official "Church of Ireland" but in Presbyterian churches of the area. Many of my CALVIN/COLVIN family's vital events were recorded at Clones Church of Ireland as well as Stonebridge Presbyterian Church where they were members from an early date.
Tithe applotments (1820s-1830s) would give you possible townland locations for Ferguson and Wiggins families in the Clones parish area, and churches near those townlands would be likely to have your ancestors' records.
For an earlier generation (parents of William Ferguson & Margaret Wiggins), the 1796 Flax or Spinning Wheel census would give you an idea of Ferguson/Wiggins locations.