Hi Elwyn
According to their New Zealand death certificates, Robert SCOTT junior (~1814-1890) is the son of Robert SCOTT (farmer) and Mary STEWART. He married Rebecca SCOTT (~1820-1906), the daughter of John SCOTT (manufacturer) and Matilda ALLISON.
Further (from their death certificates), Robert and Rebecca were both born in Londonderry, and were married in Curragh, Ireland in ~1839. Their first child, Joseph SCOTT, was supposed to be born in Castlefinn in 1844 but I have yet to find record of that. The next four children, Sarah, Rebecca, Stewart Allison, and Elizabeth, were baptised in Donaghmore Presbyterian Church in 1846, 1848, 1852, and 1854, respectively. Sequent children were baptised in the First Derry Presbyterian Church in Londonderry (and so my interest in Griffith's Valuation).
In terms of Curragh, there are two Curragh townlands in County Londonderry; one in the Civil Parish of Maghera (in the Registration District of Magherafelt) and the other in the Civil Parish of Macosquin (in the Registration District of Coleraine). There is also Curragh townland in County Donegal in the Civil Parish of Leck (in the Registration District of Letterkenny). Currently trying to work out which Curragh, but my current hunch is the one in County Donegal, but this is a work in progress. This is largely due Rebecca's parents living in Raphoe, County Donegal at the time of their deaths. The death of Rebecca's mother (Matilda SCOTT) was recorded in Raphoe in County Donegal in 1872 (I believe the informant was her son, John SCOTT) and her the death of her father (John SCOTT) was reported in Raphoe in the Londonderry Standard in 1861.
In terms of Matilda CUNNINGHAM (nee SCOTT), (~1820-1894), the wife of George CUNNINGHAM, her Austalian death certificate (New South Wales) states her father in Robert SCOTT, a farmer, but the mother is Matilda, surname unknown.
As I said, my working hypothesis is that Robert SCOTT (~1814-1890) and Rebecca SCOTT (~1820-1906) are brother and sister (I have DNA matches to descendants of Robert in Australia).
Kind regards
Eric