The research technique named Cluster Genealogy can be especially helpful to those of us doing research on our Greek immigrant ancestors.  Many of them arrived in the United States, Canada, Australia or other countries, and immediately lived in neighborhoods with other Greeks, many times a relative.   My paternal grandmother lived with her three brothers.  When I found her on the 1920 Census I was able to find her sister and husband living in the same building and a cousin living next door.   My maternal great-grandfather has been elusive.  After a very long search, I finally found him on a passenger list, but nothing after that.  I know he lived in the Greek Delta, Chicago's Old Greek Town, but since he was probably a boarder, I can't seem to locate him.  I am planning to use this Cluster Genealogy research technique to see if I can find additional information about him.  Following is an excerpt from    GUS'S GENEALOGY BLOG ...