I've been analyzing the Iskaheen RC baptism records & other sources and it looks to me as though there are the following McCallion groupings: Aught, Glackmore/Meedinmore, Gortnamona/Clunelly and Iskaheen.
Glackmore & Meedinmore are within walking distance (with Three Trees between). Clunelly is to the East and Aught is to the West. Marie mentions Quigley's Point which is East of Clunelly. I can't find Gortnamona on the map but I assume that it was in the area of Quigley's Point. Iskaheen is south between Three Trees and Muff.
Patrick Ruddy & Keith Brehmer fall in the Meedinmore group starting with Denis McCallion (~1800 - ?) & Mary Sweeney (~1805-?). This line is Denis (1800)/Mary Sweeney -> Denis (1833)/Mary Ruddy -> James (1867)/Annie Crosson -> Bernard Ruddy/Margaret McCallion -> Patrick (don't know about Keith's relatives but know they are cousins).
I (Steve Campbell) fall in the Glackmore group starting with James McCallion (~1799-1870) & Mary Laughlin (?) (1800-?) -> Michael (McCallion) Campbell (~1833) & Margaret Logue -> James R. Campbell & Mary Logue -> Weldon Campbell -> me.
Marie and Dennis Reilly fall in the Gortnamona group starting with Edward McCallion (~1815-?) & wife Mary -> James (b. 1848) & Nancy Barr -> Michael & Ellen Bradley (to Marie), Denis & Margaret Doherty (to Dennis Reilly) and possibly James & Mary Anne Deeny.
It seems possible that James McCallion (b. ~1799) of Glackmore & Dennis McCallion (b. ~1800) of Meedinmore could be brothers. The Meedinmore & Glackmore groups seem to be closely related. My great-grandfather Michael (McCallion) Campbell was from Glackmore and his wife Margaret Logue was from Meedinmore. They are related to Margeys, Feeneys, Logues, McDevitts & McDaids.
I probably have some of this wrong but it's helped me make sense of things. I believe that there's a good chance that I'm related to Patrick & Keith but less so to Marie & Dennis. Ironically, I was born in Pacific Northwest but live in the Boston area where Dennis' relatives immigrated in the 1900s and changed their name to Campbell!
Any comments & corrections are appreciated.
Steve C.