If the informant on Robert Boyce's death certificate was correct then he was born 10 Apr.1864 to John Boyce & Mary Friel.
Marriage for John Boyce & Mary Friel (1856)
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https://familysearch.org/pal:/MM9.1.1/FGC2-7M3Children-
William (1870)
https://familysearch.org/pal:/MM9.1.1/F5NH-MB5Thomas (1873 Garvagh district)
https://familysearch.org/pal:/MM9.1.1/F5FP-CPL* St. Guiare's Parish Church (Church of Ireland) Aghadowey, 1 May 1856 John Boyce, full age, bachelor, labourer, Maevemanougher, son of Robert Boyce (farmer), to Mary Ann Thiel, full age, spinster, Meavemanougher, daughter of Edward Thiel (no occupation listed).
Maevemanougher may have only been where the bride and groom were living in 1856 but this marriage might be for the same Boyces as John-
Coleraine Registry Office, 8 Jan.1851, Mathew Boyce, weaver, Meavemanougher, son of Robert Boyce (farmer), to Eliza Young, Meavemanougher, daughter of Alexander Young (farmer).