Mary Mulligan b 1877

Hi, I am searching for a Mary Mulligan likely born in county Tyrone. I know Mary was born April 1877. She immigrated to New York in 1897. She is a new ancestor and I found her by researching my gt Grandfather Norman Mulligan b. 1893 in Clogher. Norman's father was John Mulligan. I wonder what if Mary was John's sister. The New York passenger list for Norman visiting New York in 1909 says he visited his aunt. " Mary Mulligan.". The Mulligan family were Presbyterian.