Ballykeel & Drumlough

I am hoping to connect with the Jess family of Ballykeel.  My ggrandmother was Mary Ann McCann that married Robert Coulter in 1876. They lived in Drumlough although Mary Ann moved with her children to Belfast in the 1901 Census.  My grandfather is their youngest son,  Richard Grubb Coulter that married Eva Wright in 1917. I do not know the name of her mother, however, on their marriage licence William Jess of Ballykeel is listed as her father.  My mother has a very vague idea that Mary Ann's mother might have been named Mary.  I do not have a birth certificate or death date so would like to connect with someone in the family that might understand the surname discrepancy.