In this topic so far, my feelers can't sense what information (especially names and locations) is sound and what information is anecdote/lore/conjecture and therefore potentially wrong. For example, shanew147 previously posted "not sure what information you already have ... do you have a later census or other listing for William and family ?" and the response was to say that "What I know..."... But how do you know, what is the basis or derivation of your information?
In the absence of potentially unreliable information, is there a possibility that Deborah Harper have been a.k.a. Margaret? I ask that because, notwithstanding the previously posted Dublin 1856 marriage of Henry Giltrap to Deborah Harper, on 11 September 1854, the Registrar of Ballina Registry Office (County Mayo, nowhere near Dublin), registered a marriage of a Henry Gilltrap to Margaret Harper from Enniscrone, both were servants, unmarried (bachelor/spinster), his father was recorded as John Gilltrap, a teacher, hers as William Harper, a shoe maker, Andrew Mosgrove and Harriet Mooney witnessed, it was a protestant church marriage.
So is this just a co-incidence? Maybe. But can you provide a bit more background to the basis of your information, for example, how do you know (what evidence do you have) that William (or John) Giltrap married an Annie Evans, for example?