Fam takes place a few years after the first series and Dio survived. other familiar faces should be popping up soon since we've already seen Tatiana and Allister, who boarded the immigration ship (exile) together with Claus, Lavie, Alvis, Mullin and Dunya.
they are probably not the last ones to come back to earth because there are quite a number of space colonies out there besides Prester. although, they late by 65 years because they've forgotten the existence and true purpose of Exile.

anyway, you guys should really check this out as it helps fill up a lot of plot holes: http://lastexile.wikia.com/wiki/Timeline