Cindysw
I looked on Rootsireland as that is the one place online that may have records that go far back enough. I didn't see any births or baptisms.
I found one CofI marriage in Lower Fahan. Thomas Porter of Lr Fahan, father Robert, married Mary Quigley of Lr Fahan, father John. on 04 Apr !853. Could be a brother to Sarah.
Another is William Steele of Lr Fahan to Annie Porter of Lr Fahan, father Robert, on 04 Oct 1864. A sister?
The Quigleys stayed in Tullydish but there are no Porters in Beauville, Keeloges and Clonglash in 1901.
mab