Geoff has this covered...from his site there is a listing of the Family portrait (below) and a listing of who is in it:



(l-r) Douglas (Kay's husband), Kay, Anthony (next to mommy). Above, Tom's family: Frank, Andrew, Theresa, daughters. Sonny's twins appear to be on top. Old woman (Sandra?) and man? Below, Johnny Fontane. Center, Archbishop Gilday, Michael, Mary (next to daddy), Vincent, Don Altobello. Another set of young twins?
Ages in 1979: Michael (59), Connie (52), Kay (52), Theresa Hagen (59), Anthony (28), Mary (22), Victor (30), Michael Francis (24), twins (now named Francesca & Kathryn, 37), Frank Corleone (39), Santino Jr (32), Vincent (31), Frank Hagen (39), Andrew Hagen (37), Hagen daughter (26), Hagen daughter (21)