Thanks Lorna for getting in touch. James (b.1825) also had a brother called Robert and one of his descendants in Australia (John McKee (( he won't mind me referring to him)) ) has done a huge amount of work on the McKee side.
Unfortunately the whereabouts of James McKee/Mary Jane Hamilton after 1881 is a mystery to me. Perhaps, as you research their children it will become clear which remained in Northern Ireland and perhaps provided a home for their parents in old age.
