Need help with a phantom—Thomas O'Connell

Question

I know very little about the O'Connells in my family tree other than my father, Phil, and his immediate family. I know my grandfather had at least one sister, Nellie (O'Connell) Murphy, who, like my grandfather, also immigrated to the United States. This name was found on my paternal grandparents' (Mary Josephine (Cloonan) O'Connell and John Francis Patrick O'Connell) 29 June 1918, Parish Marriage  Register. John was living in Pennsylvania at the time of his marriage. His occupation was "Shipbuilder." I know that the other witness, Annie (Brown) Root, is my grandmother's cousin by marriage. I need to update/add the rest of my grandmother's family. 

Is Thomas an uncle? A cousin? A brother? Or just a friend? I have a fuzzy recollection that my grandfather may have had a brother named Tom, but cannot find any other records to confirm. If Tom is his brother, I think I may have misidentified John's father, Timothy, as I have not been able to locate any Irish family records listing John and Thomas as siblings.

Thank you!

Answer 1

Using the Wikitree Browser add-on, I did a search on Ansestry.com. I found: 

One tree entry: 

Father	Benjamin Patrick O'Connell
Mother	Catherine O'Connell
Birth	29 Oct 1891 New York City, New York, USA
Death	27 Oct 1918 New York City, New York, USA
Residence	1917-1918 New York City, New York, USA Aso found:

 A Find-a-Grave, Probate records and some military records.