Have you obtained the marriage certificate of John & Julia which would confirm the names of their fathers.
They were 23 and 22 at marriage in 1885.

1881, Marown, districtr 1, schedule 22, Airey Playdell
on the Kermode farm
John T Cain, servant, unmarried, 18, indoor farm servant, Isle of Man

1871, Michael, district 4, scheudle 32, Ballacoma Beg
Thomas Cain, head, married, 40, labourer, Patrick
Catherine, wife, married, 39, German
Elizabeth, daughter, unmarried, 10, scholar, German
John Thomas, son, unmarried, 7, scholar, German
Eleanor Jane, daughter, 3, German
Eleanor Cowley, mother in law, widow, 76, German

1871, Lezayre, district 3, schedule 7, near Sulby Bridge
Philip Comish, head, married, 40, slater, Patrick
Elizabeth, wife, married, 39, Marown
Mary, daughter, unmarried, 14, Patrick
Emily, daughter, unmarried, 12, Patrick
Walter, son, 10, scholar, Patrick
Ann, daughter, 8, scholar, Patrick
Julia, daughter, 6, scholar, Patrick
Joseph, son, 3, Lezayre
John, son, 1, Lezayre
Christian, widow,74, Bride

No relationship recorded for Christian but earlier census would suggest she was Philip's mother.