My Kneen records show Ewan and Evan are not a miss spelling, how ever there are only three Evan Kneen's listed in the IGI same as sixteen Ewan Kneen's.

I would sugest you obtain copies of revelant parish christening records, if you have names of child / children and parents and dates / parish.
I had same problem last week,the parish christening record showed both children and parents together.

Best wishes

Brian www.kneen.com