As Jess and her husband had no children, succession to the family estate became an issue for the second time since Pat Armstrong’s death. In 1959, Jess decided to break up the entail on the property, divide part of the capital between her two sisters, and use the remainder of the money to set up a trust to run and maintain the house and estate. She then gave the property with all its contents to her niece Bettyne unconditionally but with the understanding that she in time would pass it to her son, Richard Spencer. In this way, the estate would retain the family bloodline if not the name. However, in 1964, Bettyne offered the property for sale to the Land Commission. After a legal battle that lasted two years, Jess managed to regain possession of Moyaliffe Castle and its twelve-acre demesne but lost the adjoining farmland. In the midst of the difficult lawsuit, she also endured the pain of losing her husband, who died on 5 January 1965. His death led to yet another legal battle when Kemmo’s cousin Major Richard Lomer successfully contested Kemmo’s will, in which he had bequeathed Ballinacor to Jess.
Jess’s final years were devoted to keeping Moyaliffe Castle safe for the future. She eventually bequeathed the property and its contents to a distant relation, Robert George Carew Armstrong of Natal, South Africa. She also spent much time sorting the family papers and arranging and preserving her brother’s letters written during the First World War. She never stopped missing Pat. On 20 August 1981, she made the following entry in her diary: ‘Today is Pat Armstrong’s birthday anniversary … He was such a wonderful brother to me always, and how I loved him. How different things would have been now, if he had not been killed in 1917.’
Jess died at Moyaliffe Castle on 13 February 1982 at the age of 88. Her successor, Robert Armstrong died a year later, and left Moyaliffe Castle to his son Graham. Although Graham and his wife Susan visited the property regularly, managing it remotely from South Africa proved too much of a challenge. In 1999, they sold the house and donated the family papers to the University of Limerick.