Thanks Aghadowey for your comments and information.
As stated earlier on this post, I am new to Irish records, geography and Counties.
Rachel had no date of birth on the headstone, just date of death and age. I have seen it.
And yes, dates can be troublesome. Walter, Rachel's husband was a lay preacher and well know in Avondale, Ak where they both died. Family legend was always that Rachel had not been truthful about her age. We can only imagine that family papers came to light after her death and hence the age on her headstone. I really doubt they would have left her headstone engraved with incorrect age.... but...
My initial information came from Ros Davies surname site where I found Joseph Graham b1807 as child of Thomas Graham and Margaret Dunn. Hallmark sent me the death details for Joseph and he died at Ballycarngannon, Drumbo, 5 July 1880 aged 73. I only had the death notice Belfast Newsletter and it said, died at his residence Boardmills.
Joseph had a brother Robert b 1809 (from Ros Davies) and he died Idaho 1893.
https://www.findagrave.com/memorial/68354951This memorial links his parents to Thomas Graham and Margaret Dunn. My DNA links to Robert's family in USA.
It's nearly midnight down under and I need to sleep. The information I have may not be perfect but this is the first time I have had anything really concrete to start with in Ireland.
I will be investigating all information given to me today.
Thank you
Penny