The townland given for the 2 girls marriages was Derryhale. I searched Griffiths Valuation (1864) and there’s no sign of a Brunkard family. However there was a house, forge & land on plot 2, occupied by John Wright. Death registration started in Ireland in 1864. There’s no sign of John Brunkard’s death, nor of any spouse. (There are no Brunkard deaths in the Armagh registration area 1864-1901). My guess is that both John and his wife had died prior to 1864, and the forge passed to John Wright.
Tradition was to marry in the bride’s church which, in this case, was Mullavilly Church of Ireland. Their baptism, marriage and burial records start in 1821 (which is possibly when the church opened). There’s a copy of those records in PRONI in Belfast and there is some coverage (years not given) on rootsireland which is subscription. You could search those records for the parents burials and the children's baptisms, though it’s possible Isabella was born before the records start.
Derryhale had about 60 homes in 1864, and only 1 forge. So the likelihood of there being 2 John Brunkards, both blacksmiths, in the same townland at the same time, seems fairly low.
The tithe applotment records of 1833 list a John Brunkard in Cornascrebe townland (more commonly Cornascreeb) which is immediately adjacent to Derryhale, so that may be where the family lived then:
https://www.irishgenealogyhub.com/armagh/tithe-applotments/kilmore-parish.phpBrunkard is not a common name in that area. No Brunkards and no forge in Cornascreeb in Griffiths.
Isabella looks to have remarried in 1875 to Thomas Morgan. She married in a Catholic church, so had probably changed denomination:
https://www.irishgenealogy.ie/files/civil/marriage_returns/marriages_1875/11192/8101415.pdfThe certificate states her father was dead by that date.
This may be James McMahon’s death. Informant was Isabella. He was a pensioner which usually implies a military pension:
https://www.irishgenealogy.ie/files/civil/deaths_returns/deaths_1874/020646/7244385.pdf