I noticed that James Greer’s death was reported by Alexander Greer, who appears to be his son. Alexander died in 1886.
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1886/06243/4787358.pdf
The Will of Alexander Grier late of Aghaboy County Antrim Farmer who died 17 June 1886 at same place was proved at Belfast by Mary Agnes Grier of Aghaboy Widow one of the Executors.
The will is on-line and in it he left everything to his wife.
Alexander married Mary Henderson in 1864:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1864/11615/8275639.pdf
They married in Duneane Presbyterian.
The Valuation Revision records on the PRONI website show that in 1895 the farm passed to John Rainey, so perhaps a relation. Here’s that family in 1901:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Drumanaway/Aghaboy/941616/
This looks to be John & Maria’s marriage at the OC Presbyterian church in Randalstown:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1875/11190/8100496.pdf
Family were still in Cranfield in 1878:
https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_returns/births_1878/02968/2087088.pdf
I can’t see any immediate connection between the Greer and Rainey families but there presumably was one. Did the Raineys perhaps just buy the farm?
The Greer farm was 83 acres (plot 3) in Griffiths which would be very valuable. I don’t see a will for Mary Ann Greer so don’t know how she disposed of it. I assume it was her death c 1895 that led to the change of tenant. 10 acres (plot 1) went to the Henderson family, presumably her own relatives. Maybe they inherited the lot under intestacy laws and chose to keep some land and sell the rest?
PRONI has a few of Shane’s Castle estates records including 1829 & 1831 tenants and their leases T2518/1 & 2. If the Greers had 3 lives leases you might get a little more information about them from that. (Many tenants had 3 live leases issued in the 1780s and 1790s and they may list relatives and their ages).