It was Hugh's father, mother and any siblings I was hoping to trace.
--I looked at records on RootsIreland, but I could not see Hugh's baptism nor baptisms of any other children of Patrick and Ann.
--There are baptismal records for children of a Patrick McArdle and Ann Keenan in Co. Louth from the 1850s to 1870s. It seems impossible that these are Hugh's parents. Hugh was probably born around 1830.
I don't know if Hugh was orginally from this area or not?
--He was living in Ballybrick townland in Down when he got married, as was his wife Jane. Not sure where you got the record saying she was from Tyrone?
--Keep in mind that in the 1840s/50s, a great number of people were farmers and lived their whole life on the family farm or a farm they married in to. Transportation was by animal and cart, or by horse. It was not common for people to move far from where they originally lived--except, of course, if they emigrated. It is likely Hugh was born in or near Ballybrick.
Particularly as his wife Jane was from County Tyronne. Her maiden name was O'Neill so I'm guessing her witness was a relation of hers. As far as I can find out she didn't have a sister. Two brothers, Thomas and Bernard. Thomas went to New Zealand and Im not too sure about Bernard.
--Yes, the O'Neill witness was very likely a relative. Usually the sponsors were siblings.
I wondered if Patrick McArdle, Hugh's father might have been buried in a cemetary local to Annaclone or if there were any records of his parents having more children either in Annaclone or nearby I've also never found a birth entry for Hugh.
--There would be no birth record, only a baptismal record. I'm not sure if records exist for his area; maybe one of the volunteers might clarify this.
--If Patrick died after 1864, there would be a death record at irishgenealogy.ie. And yes, he would likely be buried in the Annaghclone cemetery.
I believe his mother Ann nee Keenan came to Scotland with the family and she died there.
--Have you seen her obituary, death certificate, headstone inscription? These may shed light on the family.
I hope this helps.