Thanks for the suggestion to try the Ellis Island site. I've done that (and in fact, think I did find my grandfather, Nicholas, there). And, I'm a subscriber to ancestry.com so that's been useful too.
Re the Stavropoulous link: it's a bit distant. Paul Kanavos married Bessie (unknown).
Their daughter (also named Bessie) married a Stavropoulos. I don't know his first name. They lived in West Roxbury, Mass. - and she died this past year. She was the only relative my mother had any contact with.