Name: Mary Stevenson Gender: Female Birth Date: 25 Aug 1864 Birth Place: Tartaraghan, Armagh, Ireland Father's Name: James Stevenson Mother's Name: Eliza Cowan FHL Film Number: 101090
Name: Elizabeth Stevenson Gender: Female Birth Date: 1 Sep 1867 Birth Place: Tartaraghan, Armagh, Ireland Father's Name: James Stevenson Mother's Name: Elizabeth Cowan FHL Film Number: 101150
There is a possible marriage in the registration district of Lurgan in 1863:
Name: James Stevenson Date of Registration: 1863 Registration district: Lurgan Volume: 7 Page: 389 (click to see others on page)
Listed on the same page is an Elizabeth Cowan.Stewart Cowan is also listed on the same page.
Tartaraghan Parish is now part of Portadown in the area known as The Birches. Getting the baptisms and the marriage should provide you with the name of the actual townland from which they were from, and the marriage record could name her father.
From Griffiths Valuation, there are only three Cowans in Tartaraghan in the 1848-64 timeframe: Andrew, James and John.Andrew & John in Clonmakate, and James in Cranagill.
Another researcher is working on this family (Stewart's descendants) who seems to know that Elizabeth's father was Andrew: