Can't match John Cain but can trace Margt Cannell who had a 2nd marriage (no ch) to John Roney

Margt is I think d/o John Cannell + Anne Quilliam - m Pat 17640804

Ann Quilliam is I think d/o Alice White als Quilliam als Clark + Henry Quilliam m Ballaugh 17261119 where noted Henry Quilliam kk patrick;ac this p - Henry's will of 1741: lands cronk moar;son john + his 5 bros & sister;wife alice quilliam als clark;robt & patrick quilliam uncles on fa side superv.
Alice will 1784 epis Patk - d dec 1783;4 ch robt quilliam,elinor Quilliam (w/o Robt John Kermode),Catharine Quilliam (w/o Patrick Sayle),and Ann Quilliam (w/o John cannell) + eldest son John Quilliam (had mar set) + Wm White (mar set)(admr) [see NSS Oct 1757 3]
a Wm White was a witness to marr of Ann Quilliam + John Cannell (John noted as of Kk Arbory)
Ann Cannel [als Quilliam] will 1799 episcopal Arbory - dated 10 sep 1799;husb john;ch henry,margt cain als cannell,cath quirk als cannell,thos,hanna?,patk,richd,mary(exex)
There are no bapts I can find for this family other than for Patrick bapt Arbory 17660305 (+ I think bur bur Arb 18341019 age 72)

John Cain m Margt Cannell Rushen 17840424 - noted as both of parish witnesses parish clerk + Thos Cottier
the name Cain is relatively unusual in Rushen (common elsewhere)
There is sale SSS May 1787 #98 dated 25 Jan 1785;Edward Millar + wife Ellinor als Watterson sell for £31 to John Cain(shoemaker, Rushen) a house recently erected being part of a qtrland lately purchased from Henry Gawn(Rowany)[SSS Oct 1777 87] situate near Port Iron rent 1d; Witt Edmund Christian, Thos Cottier
There are 2 known children to John + Margt - eldest Wm bapt Rus 17851218 + John bapt Rus 17880710
my estimate is that Margt is in early 20s at marriage thus would have expected several more children
however there is an unusual entry in Rushen burial reg for a John Cain bur 22 Feb 1803:
in this parish about 20 years from Douglas, died an unnatural death on Saturday last, on monday following was found drowned beyond Fleshwick, a jury brought in a verdict of insanity
There is a will for a John Cain in Rushen in 1805 however still to be looked at
but a Wm Cain sells property in deed CTD Mic 1809 21 - dated 22 Mar 1808;William Cain(Rushen) sells for £470 to John Roney(Rushen) my interest in the houses, lands + premises of Breagal beg situate in qtrland known as Currin's qtrland + also my property situate in Portiron [Port Erin] known as John Cain's premises [see SSS May 1787 98] all of which I am entitled by will of my father John dated 17 Sep 1798 - £260 now in possession and £221 to my brother John when he attains 21 years; Witt Thomas Cubbon, John Duff
John Roney marr a Margt Cain (widow);both rushen;by special lic Michael 18031224
John Roney places all his half of purchased property in trust for his wife SSS Oct 1830 66 dated 24 Oct 1821 (suggests that debts were mounting up) and d intestate 1825 - admin petn by wife Margt that d intestate; John Fitzsimons appt admr [widow Margaret Roney's name erased + Fitzsimons overwritten]; accts [? debts as Roney had placed his half of all purchased lands in trust for wife which in 1830 was returned to her]
Margt is found in 1841 in shared property with widower Cath Quirk als Cannell who is I think her sister and died 1844 aged 79

A most unusual family with links across the Island