Hi Ross. Yes please, I'd be interested in the file. I'm at egelling at shaw dot ca . I don't think I have anything on a NZ connection with this part of the family.
Your note is a bit cryptic but I think I've got it. John Gelling & Catharine Killey's second son of five was Robert (1744-1807), a miller of Ballagraw. He was married to Jane Kelly and their third son Thomas died an infant.. This is where I got confused until I looked further. Glad you said "three generations later".
Robert & Jane's second son Robert (1779-1835) was married to Ann Kelly and it was their fourth son of five, Thomas (1807-1866), who married Margaret Kelly in Marown 1830, had 11 kids that I counted, and went to Australia on the "Fortune" in 1853 with his surviving 6 children. Ultimately to Tumut NSW as you have said. My notes say there is an article about them in the IOMFHS Journal Feb 1988 which has the MI information from the local pioneers cemetery. Jean sent me that in 2009.