Steven.. My Grandfather was Domenico Castiglia who was one of Francesco Castiglia's sons.
I labeled Francesco wrong he was only my Great Grandfather..
Francesco married twice. His first wife in Italy Giovanna Borea 1850-1870 died. Francesco had
two brothers Luigi [Costello's father] and Antonio and Guiseppe. After his first wife died Francesco[1846-1902]
married Marianna Iuele [1857-1943] and they had Luigi Castiglia [1890-1955], Domenico Castiglia[1880-1957],
Concetta Castiglia[not Costello's sister][1887-1983]. I grew up in the same home as Marianna, Domenico,and
Concetta in Westport Connecticut where the NYC Castiglia-Costello- Aloise family visited. I was young
and only saw Costello once at a funeral in NYC but I am not sure whose funeral it was.
I have on Ancestry.com a private family tree INCLUDING Castiglia-Costello family, I can invite you and Dana as a guest to look at and I believe this will make it more clear. Some of the original documents from Italy are also on this site.
I hope the above give you a better perspective of the relationship.. I believe
Great Grandfather Francesco would have been Frank Costello's Uncle.