Surnames of Dinsmore Courtney Martin

I have come to believe that my great-grandfather Joseph Dinsmore of Ballymoney is actually the out-of-wedlock James Dinsmore whose father was Hugh Dinsmore and mother was Nancy (Anne) Martin. The dates of birth match and no records after the baptism exist for James Dinsmore that match the age and parents. Perhaps Jos Dinsmore looked like Jas Dinsmore to the priest when he was recording the birth in the official church records. With that said, I have learned that Nancy (Anne) Martin had another child out of wedlock -- Robert Courtney. His father was Thomas Courtney. I have Nancy Martin's death certificate -- she died 14 May 1896. I have no information on Robert Courtney, who would be my great-grandfather's half-brother. Are there any Courtneys in this group who may be descendents of Robert or Thomas Courtney? Any information would be helpful. Many thanks. All best, Christine Dinsmore