I have one other marriage of an offspring of a Wilson, namely Maria, born 1843, daughter of Wilson McIlhaggo married to Samuel Winning on 12 May 1868 at Antrim Civil Registrar's Office. Maria was from Newpark Antrim, though this may be where she lived as a Servant and her father may well have been the same Wilson, a farmer from Racavan. Her witness, Mary Carnaughan does not I'm afraid add any further clue to this family's identity. We may know who William and Maria's father was, but not her mother as I have no marriage of any Wilson around 1820.
I do have one late birth of a Wilson, son of James McIlhagga of Eglington on 30 December 1880. It looks as if Wilson was the surname of a mother or a grandmother and it is just possible that if we were to go back a couple of generations in the Eglington family we might find a Wilson from Racavan. James of Eglington married a Johnston whose mother was a Greer, so no Wilson there. James was son of Nathaniel and Ellen McIlhaga. It is possible that Ellen's surname was Wilson and that in addition to James she may have had a son Wilson, though at present this is entirely in the realms of speculation. There was indeed a Nathan McIlhaggar, born about 1804 in Carnmoney, who did marry an Ellen Wilson, born about 1809. They married in Carnmoney on 21 May 1830 and they did have a son James. However, to the best of my knowledge neither he nor his parents had a son who was named Wilson, so the temptation to identify the Eglington family with the Racavan family seems to have run into the sand.
There is one other Wilson McIlhagga, born in 1875 to John McIlhagga and Eliza McCullough of Connor. Was he named after his paternal grandmother? Sadly we don't know her name! So we have come to the only other Wilson references I have which are second names. John W. McElhago was born in 1865 and died in 1867. James W. McIlhagga, born 1871 was son of Henrietta Wilson, so must have been named for her and another James W. McIlhagga, born 1894 was a nephew of the 1875 Wilson, so clearly was named after him.
We do have a 'late' female, Jane Wilson born in 1904 to William Hugh and Maggie McIlhagga, who was possibly named after her great uncle, one John Wilson McIlhagga. a farmer who died in 1896. Now he had son William who according to the IGI married a Jenny Stewart on 2 Jan 1868. Time-wise we are in the right ball-park, and I think we have come full circle! I think Jenny Stewart and Jennifer Stewart were one and the same person, and that the IGI's date of 2 Jan 1868 should be corrected by the Ulster Historical Foundation's date of 3rd Jan 1867. Conclusion - William's father was simply using his second name only when he was being 'father' at both William's and Maria's weddings. John Wilson McIlhagga's father was one William McIlhagga, born about 1810 in Maxwell's Walls, in the parish of Connor. John Wilson, known as 'Wilson', was the youngest of nine siblings.