I have a Hugh McElmoyle born about 1830 Derry married a Margaret Hodge (?) in 1849 Derry County. Emigrated to Summit Hill, Pennsylvania in 1870's. They show children Hugh (1860), Henry(1861), James Alexander (1863), Samuel(1865), Robert (1869), and Martha (1872) born in Ireland. As they married in 1849 I might assume there were other children who did not emigrate with them. I have found James Alexander, Samuel, Robert and Martha all with fitting birth dates on Irish Genealogy site in Derry Genealogy Center listings.
They attended Presbyterian Church in Summit Hill, but have not found much else.
Any connections to your McElmoyle's.
Bonnie Paton-Pietruch