The one glitch to this is that there is a 1724 Braddan will of "John Gelling of Town of Douglas departed this life 2 Nov 1724 ... To beloved wife Margret Gelling alias Kneal all Houses, etc ... & Exec'x". See transcribed will on will index. This is a completely different John Gelling, and I think he's a son of a Paul Gelling.

At this point I still don't know who was the wife of John Gelling who died 1732/3, father of the John G who carried on Ballamillagyn. His will mentions an "eldest son John" [he got Ballamillaghyn] and also another son John, "the son of Ann Kneale" named executor. I don't know anything more about this latter John and how Ann Kneale got into the act.

The parentage of the John Gelling who married Isabella Cavendish 1788 Braddan remains a mystery too. I figure John will be either the one buried 23 Sep 1837 age 69 or 15 Sep 1840 age 70, both Braddan. There's an 1838 Braddan will too. Isabella was buried 2 Feb 1856 Braddan age 89 and there's a possible will for her. Here's what I have for their children so far:
1. Mary b 1788 as Mary Cavendish before marriage.
2. John b 1790.
3. Robert b 1792
4. William b 1794. Prime candidate to match your ancestor who md Margaret Quine 1816 Braddan, 9 children. Wm died 1874 Onchan.
5. Anne b 1796
6. Thomas b 1799. Perhaps the Thomas bd 14 Jul 1836 Braddan age 36. Will on index. Unknown if he married.
7. Margaret b 1801
8. Sarah b 1803. Had a child Elizabeth by Felix McKewin 1825, then married John Shimmin 1833 & 8 children. She is a widowed lodging house keeper at Hope St Douglas age 57 in 1861, but I've lost her after that. The 1825 child Elizabeth (aged 16 and 26) matches well to be the grandaughter living with Isabella Gelling at Shaws Brow Douglas 1841 and 1851.
9. Isabella b 1805. Md Philip Shimmin (son of Hugh) 1827 Braddan & 13 children. Bd 1878 Ballaugh.
10. Richard b 1807. Perhaps the one who married Elizabeth Hinchcliffe 1835 Manchester. One child Victoria Isabella b 1840 Liverpool who married Aaron Brookes 1858. Richard died 1881.
11. James b 1810 and died 1814.

Does this match up with what you have, Marg?