Who are these people?

As you know, the Mulcahy family disappeared from 85 Luqueer St. in 1910. In the late 1890s, it's given as Michael's home address in the Brooklyn City Directory, and in 1905, Michael and two of his sons, returning from Ireland, give it as their home address. In 1900, however, they don't appear on the census. Who does appear on the census are the Thommassen, Casserly, and Trithy families. I'm particularly interested in the Trithy family. They're listed as Thomas and Mary E. Trithy, both born in Ireland, and his occupation is N.F.D. Repairs. The reason this interests me is this 1931 obituary I found on the Brooklyn Genealogy page:

THOMAS TRIHY died Wednesday at his home, 485 Pacific street. He was born in Clashmore, County Waterford, Ireland. He was employed in the Telegraph Bureau of the New York Fire Department. He was a member of the Civil Employees Association of the New York Fire Department. He is survived by his widow, Mary E. McCARTHY TRIHY; a brother, James W., and two sisters, Mrs. Delia MULCAHY and Mrs. Victor O'NEILL. The funeral will be held at 10:30 A.M. Saturday with requiem mass at the Church of St. Agnes. Interment will be at Calvary Cemetery, under direction of W.A. MARTIN, 764 Washington avenue.

It appears that this Thomas Trihy had a sister named Delia (oftentimes a nickname for Bridget) who married a man named Mulcahy. Could this be the same Thomas Trithy (who also worked for the Fire Department) who had lived in the 85 Luqueer St. that was owned by our Mulcahy family? We have no records of any of Michael Mulcahy's brothers marrying women named Delia and/or Bridget. His two known brothers in the US, James and Patrick, are supposed to have married women named Molly and Catherine, respectively. There was also, we hear, a brother named John who stayed in Ireland, and we don't know anything about his personal life.

It's all so very coincidental. Who are these people?