Hi Edith.

Being Kerruish it is likely that she came from Maughold where there were many Kerruish/Kerrish families at that time. I found two Jonys in Maughold bapts, both daur of John Ks (no mothers given). One on 8 Nov.1666, and the other on 21 June 1680 daur of John Kerrish. As she died leaving young children this latter one seems the most likely.

Constance Radcliffe has her on her Cardle chart where she has a queried John married Margaret Corteen as the brother of Robert Kerruish the heir of Cardle (mentioned in Robert's will: www.iomfhs.im/lawsons/twill/1675_076.html), but this is wrong. She has the same John & Margaret Corteen on her Glen Vullen chart with John b.c.1645, and married 1670 which is correct. He was therefore unlikely to be the brother of Robert of Cardle b.c.1600. At Glen Vullen CR has him as queried son of a Robert Kerruish.
John and Margaret Corteen had only 3 sons - not the 6 children, including Jony, given for them on CR's Cardle chart, and who would have ranged in dates of birth from 1671 to 1698. We know for certain that Jony was not the child of John Kerrish and Margaret Corteen because John died shortly after the birth of son 3: www.iomfhs.im/lawsons/twill/1677_000.html. Margaret's will is under Corteen: www.iomfhs.im/lawsons/twill/1705_009.html

There were at least two John Kerrish fathers having children bapt following Jony's 1680 bapt. For example there was a Margaret daur of John K bapt in July 1691 and a Mary daur of John K bapt in August the same year. CR has Margaret as Jony's sister, and omits Mary. Other children of a John K were an unnamed child bapt 1685/86, John bapt 1694 (Ballaknock at bapt), who CR thought started the Kerruish Ballafayle branch with his wife Mary Kneale 1704-1763. Married 1725; John 1694-1753 on her Ballafayle chart. He is also given as a sibling of Jony's on CR's Cardle chart, but they are clearly a later generation than being possible children of Robert's brother John b.c.1605-08 as given there (without dates). Possibly grandchildren of John.
Not on CR's Cardle chart were also two Roberts, sons of John Ks, one bapt 12 Feb.1697/98, and the other bapt 19 Feb 1697/98 (Callom).

On Jony's 1709 will one of the supervisors of her children was Robt. Keroosh. If one of these above Roberts was her brother he would be too young. An uncle?

Sorry this isn't much help, but you can at least omit John Kerruish and Margaret Corteen as her parents. Is Ballaragh near either Ballaknock or Callom - if that was a place name?

Sue