suspect your Mary is Mary Oates but I never found a marriage - there are 4 bapts two of which match the 1851 in Douglas 1st 2 Elizabeth 1835 + a Mary Ann in 1837 at Douglas St Matthews next 2 John 1838 + william 1841 in Doglas St Barnabas

John Cain + Mary Corkill had 4 children bapt St Lukes in Braddan 1st child Christian but can't find in 1851