Seeking information about the McMahens/McMahons of County Armagh, Ireland
James McMahen and Elizabeth Ann Moore are my great great great grandparents. Their son, William Moore McMahen emigrated to Melbourne, Australia in about 1840-42, and is possibly the passenger "William McMahon" (note the different spelling of McMahen/McMahon) who arrived in Port Phillip from Grennock (Glasgow) on the Robert Benn on 26 Jan 1842. That William was a protestant from Armagh and puts his age at 27 and so his birth in 1814 or 1815. William Moore McMahen's death certificate puts him at aged 81 in 1892 which would have him born about 1811. They may still be the same person though as we know ages and spelling of names on records are notoriously unreliable.
Can anyone help me find a record of William Moore McMahen's birth in Ireland or any record of his parents James McMahen and Ann Moore or any siblings he/they might have? William married Margaret Keys of County Tyrone in Scots Presbyterian Church in Melbourne in 1846 and their children were raised as Protestants (some presbyterians and others methodists) and so his family were almost certainly protestants.
A message on a message board on another site suggests that William Moore McMaahen may have come from around Camly Macullagh, Newtown Hamilton in Armagh, but I have no evidence to confirm or deny this.
Looking forward to hearing from anyone who can assist.