Strange I should happen on your message tonight. I was just up at Calvary Cemetery south of Albany, NY two weekends ago, showing one of my daughters the grave of my grandfather, Edward F. Kerwin (d. 1956). There are at least two others buried there as well -- Thomas Kerwin (my paternal uncle, son of Edward) and his wife, Frances Miller Kerwin. Other Kerwins are buried on the north side of Albany in St. Agnes Cemetery, including Edward's wife, Theresa McCarthy Kerwin (d. 1943) and five others in the same plot. (I ordered the records on the five just today, as a matter of fact.)
I'm unaware of other Kerwins buried at Calvary, but there was a hive of them in Albany. I don't know of any Hefferman or Monahan connections, but I got interested in this family-tree business after everyone who would know much had died.