Hi Kath, just read your message. I don't know of any connection between my Patrick Green of Ballyfad and the Green family in Knockgreany. It is possible they were related but I have no evidence of this. If any one knows of a connection I would love to hear about it.
The folowing web site gives some information on the knockgreany Green family.
There is a grave in Ballyfad Cemetary inscribed "Gloria in Exelsis Deo. Erected by Patrick Greene of Knockgreany in memory of his daughter Rose Greene who departed this life 2nd sept. 1833 age 17 years also two of his children Dan and Owen who died in the first year of their age. Also the above Patrick Greene who died 30 May 1867 age 69 yrs, also his wife Cathrine Greene who died 11th June 1884 aged 66 yrs" There are other Green/e graves in the local Cemetaries but they don't list where the people were from.
There were two Greens, Patrick & John living in Knockgreany in 1853 ref. Griffiths valuations, Pat rented a house offices and land from the rev. William B Forde & John was a caretaker for a house office and land for rev. William B Forde. Michael Greene was evicted from Knockgreany in the 1887 evictions. Ref. Peggy Doyle's book the Coolgreany Evictions, published 1986. This book shows a picture of Michael and his wife. A more recent book "Croghan to the Sea" by Fiachra O Lionán also deals with the evictions and has a picture of the evicted Michael Greene of Knockgreany and his family. (I purchased the latter book a few years ago in The Arklow Bookshop) I hope this is of help with your family history.