Could be Thos KEWN bapt Braddan 31 July 1768 son of John KEWN & Margt COWLEY [IGI].

Thomas KEWN married Alice [Ales] QUAYLE 3 Dec.1791 Braddan [IGI]
There were a number of children with those parents bapt at St Matthews, Douglas [IGI], including William on 8 April 1807, but some look at bit close together to be the same family. Census records would probably be the best source to sort out your families.

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