I know Edward to be father by means of elimination - Ned Shevlane's son Patrick, for whom I posted a birth record earlier, lives with "Uncle" Manus Shevlane and wife Maggie in 1911. This Manus is certainly not son of Michael Shevlane, grandfather of Patrick and father of John Shevlane who married Bridget Murphy. Therefore Manus must be a "Great-Uncle", and looking at his 1865 marriage shows Edward Shevlane as father. It also explains where Ned Shevlane (Edward) - son of Michael - got his name from! It's coming together a fair bit now I think, so I aim to push back further yet.
The Belmullet registers frustratingly lack digitisation much of the time. Moreover, as you say, some records that should be there simply aren't due to lack of recording. I have this issue with identifying parents of Anthony Kelly who married Ann Carey in 1869. I scanned every single Belmullet marriage for that year, and no luck. It wasn't recorded. This is discussed a little on two other threads - one specifically for Anthony Kelly and his family, another about Major Bingham. Any further ideas Hallmark, on this side of things? I mentioned Daniel Kelly as a possible brother? Thanks.