How certain are you that Grace Cowan’s parents were John Cowan & Mary Ann Savage? What’s your source for this information? I ask because there are several trees on Ancestry which name her parents as Edward Cowan 1839 – 1921 and Mary Emily Hemstreet 1861 -1907. Grace’s place of birth is given as Codington, South Dakota in 1887, she married William Routledge in 1905 and died in Seattle in 1982. Edward’s place of birth is given variously as Canada and Ireland. Mary’s is given as Russia.
I don’t see a marriage in Ireland for John Cowan and Mary Ann Savage 1845 onwards, though it would help to know when, roughly, they were born or married and what denomination they were. (Your information is a bit short on dates).