It looks as though it may be a long (and possibly) expensive task to pin down the Davys-Winterscale crowd in Sligo, even if Winterscale at least seems to be a really uncommon name. I have looked at the 19th Century Censuses on this side of the Irish Sea and the only Winterscales in England, apart from the descendants of John Winterscale through his only son John Francis Mair Winterscale, are a crowd of them centred on Liverpool, presumably also of Irish (Sligo?) origin. Would I be correct in thinking that you Bessie and Margaret would be cousins of your John Winterscale Davys (ie daughters of Edmund Soden's siblings) or would they be his sisters? Possibly their death certificates would pin down their parentage?
Re your exchange with Richard, Elizabeth Winterscale would seem to be the cousin of your John Davys Winterscale - that is she was the daughter of the brother (John Wintercale) of Mary Winterscale, who we think was the mother of your John Davys Winterscale.