After sitting on the baptismal certs since forever (having always felt there were clues in the sponsors' names for further revelations), AND Judith Gartlan & Patrick Bryne's marriage data, last night I looked again at the 1866 marriage extract that Tom found in the RC church logs and then the bap. certs.
Sure enough Judith's (aka Julia, Julie & Judy) "Maid of Honor"'s name AND residence were listed, and later one her HER sisters was a baptismal sponsor for one of P & J's children.(The Townland was Greaghdrumit [sp?] in Magheross, I think.)
Some of the other baptismal sponsors included Judith's cousins -- related via her mother's family (Cassidy, also discovered in the marriage data.)The 1901 Census showed a few of them living in the same townland as married adults.
Between the surname spelling variations (and errors), the lack of Census records, and horrendously expensive certs for everyone and everything, searching Co. Monaghan is like having a 250,000 piece jigsaw puzzle ... and having to piece it together across an ocean!