Hello Cafferkey,
From what I can see there are three Peter McGreal's in the Loughglynn/Lisacul area around 1850's.Two are in Driney and Cuiltyboe which are on the Loughglynn side and the member My Luck may have more info, and a Peter based in Currohopuile(Corracoggil) North which would have been centered on the area close to the current Christ the King Church, which is a few miles distance from Curraghsallagh.
The Curraghsallagh McGreal was Owen(Eugene) McGreal born around 1816. I must confess I have not exhausted searches for this line as my interests in the McGreal line have taken a broader examination of the McGreal/McGrail families at the expense of my own line.
From what I am aware from Docs is Mary Cafferkey married a Michael McGreal 26 Jan 1891 fathers are noted as Eugene McGreal and Mark Caffekey on the Church record and Owen McGreal and Martin Cafferkey on the Civil Document.Witnesses on both are Martin McGreal and Catherine Cafferkey.
Michael McGreal Died 22 Dec 1897 and Mary was left with four young sons. The sponsors on the baptisms are consistent as being Thomas Duffy,Eugene McGreal, Catherine Cafferky, Mary McGreal,and John Cafferky.
By 1911 two of the sons Michael and James had moved to England and were living with a James and /Bridget Cafferky a brother and sister, who were uncle and aunt to the young McGreal brothers. John a third brother appears in Manchester as a witness to his brother James marriage
in Feb 1920 to a Mary Blood.The Cafferky's ran a Grocers in North Manchester which James continues after their death. James appears to marry again on the death of Mary to his Sister in law Catherine.
The name Nellie or Winnie Cafferkey does ring a bell as she often played host to the families of Patrick McGreal and Catherine Dwyer the fourth brother who remained in Curraghsallagh,when they came home to Lisacul. If we are on the right track the surnames Rush, Kilheeney and Butler would be familiar to your aunt.
It is possible the Peter you refer to was a brother to Owen and part of a larger family unit originating from Curraghsallagh.
Your aunt may also know of the one remaining McGreal family in the Lisacul area which I believe is unconnected to those from Curraghsallagh.
Hope to hear from you soon.
Padraig McGreal