I don't have any specific information, but maybe we can help each other out. May family of Nelligan's is also from Castleisland, County Kerry, and family legend has it that Bishop Charles is in our family tree. However, I don't have any proof of that. My Nelligans all settled in North Cambridge, Massachusetts.
I'm at work right now and as I didn't update my tree online (bad girl), I don't have all my dates handy. However, my grandfather, Peter J. Nelligan was County Commissioner in Cambridge, MA for a number of years.
His father, my great-grandfather, also Peter Nelligan, supposedly came over from Castleisland as a very young boy. He was born in November of 1842 in the townald of Annaghmore, Castleisland. I might not have the correct spelling of the townland.
His father, my great-great grandfather, was David J. Nelligan from Castleisland, County Kerry. David was married to a Nancy Sweeney. I am trying to read David's date of death on a badly eroded headstone so I can pull his death certificate and find his parents name.