Phi Gamma Delta has "Fiji Sires and Sons" (
http://www.phigam.org/page.aspx?pid=945) as an official order within the Fraternity of Fathers and Sons who are both members of Phi Gamma Delta. This is the only example I've seen being a certain type Legacy means something official within a fraternity/sorority *after* initiation into the GLO. Does anyone know of any other groups that have similarly special Mother/Daughter or Father/Son organizations like this?