Hi, Sue and Frances,
Some comments:
1. It is possible that the Braddan marriage 12 November 1748 of John Skillicorn and Mary Kelly is actually for John Skillicorn and Margaret Kelly. The time is about right, and there is no John Skillicorn/Margaret Kelly to be found in Lonan. (As far as I know, Margaret Kelly has not been connected to any Lonan Kelly families as yet. Is that correct, Sue?)
John Skillicorn's wife was clearly Margaret. This is confirmed by her will dated 27 June 1789. Margaret Skillicorn of Lonan leaves to Dau Jane Skillicorn otherwise Corkill, son Philip, Jane Killey otherwise Skillicorn; eldest son John whole & sole executor.
2. Perhaps the "child" bap to John Skillicorn 1 October 1749 is John Skillicorn and Margaret Kelly's daughter Jane.
There is a John Skillicorn, son of John, Mountains, baptized 1 March 1751.
I had "guessed" that Philip son of John baptized 3 July 1757 is the one who married Ann Kerruish.
So, that gives us the three children of John Skillicorn and Margaret Kelly, as given in Margaret's will. I suspect there were more, not listed in the register. Perhaps died as infants or small children?
4. Frances, you seem to feel the 1757 Philip is the son of a different John. Could you be more specific?
5. Frances, where/how is it possible to view the original registers? Hae you found many discrepancies between the original registers and the 1911 copies?