I'm very interested in this dialogue, although I cannot prove any link to John Caine or Isabel Kewley at this stage. However "my" Caines were in Braddan at this time and possibly linked to the Caines being discussed here.
My line is best detailed on Tim Davis's "Manx Ancestors and other relatives" which is on the net. I am a descended of Robert Joseph Cain, then John Joseph Cain and Laurie Desmond Cain ( my father) John Joseph , my grandfather emigrated to New Zealand early last century along with some other relatives and the New Zealand Cains are the result.( well some of us)

I am very interested in contact with my wider family of Caines and have been gathering Cain(e) information for 4 years now
Gary Cain Auckland, New Zealand