Someone in Garvagh is bound to remember your granny being raised in Garvagh- will see what I can find. Meanwhile, here's a bit further back-
James Mullan's parents: 22 June 1860 Aghadowey Presbyterian Church, John Mullan, labourer, Gorran, son of James Mullan, labourer, to Sarah Jane Doherty, Landagivey, dau. of George Doherty, weaver.
James Mullin, Gorran, son of John, bapt. 4 Oct.1861 Aghadowey Presbyterian Church.
Hugh, Ballynacally, son of John Mullin & Sarah Doherty, bapt. 29 Jan.1864 Aghadowey Presbyterian Church.
George, Ballynacally, son of John Mullin & Sarah Doherty, bapt. 18 Dec.1865 Aghadowey Presbyterian Church.
[birth reg.: George, son of John Mullin & Sarah Jane Dougherty, born 18 Dec.1865]
Margaret, dau. of John Mullin & Sarah J. Doherty, born 5 JUne 1879, bapt. 25 Apr.1871 Aghadowey Presbyterian Church.
St. Guaire's Church of Ireland, Aghadowey: Erected in memory of John Mullan, late of Caw who died 21 Decr. 1903, aged 73 years. Also his son John who died 6 Feby 1914 aged 36 years. Also his wife Sarah Mullan who died 29th January 1925 aged 84 years. Also his son Hugh who died 12 Sept 1928 aged 65 years. Also his daughter Isabella who died 26th Jany 1956 aged 87 years.
Coleraine Chronicle, 31 Jan.1925: Death- MULLAN- At her residence, New Row, Coleraine, Sarah Mullan, wife of late John, aged 85 years, funeral to Aghadowey.