PRINCESS CRUISES appointed two mother-daughter stars of 1970's TV sitcom shows as the godmothers of the line's two newest ships, to be named in a dual ceremony on May 12 in Santorini, Greece, during Mother's Day weekend. Florence Henderson, who played Carol Brady on "The Brady Bunch," and Marion Ross, who played Marion Cunningham on "Happy Days," will name the Emerald Princess. Their TV daughters, Susan Olsen, aka Cindy Brady, and Erin Moran, aka Joanie Cunningham, will christen the Royal Princess. Princess is also looking for a real mother-daughter duo to join it in Greece for the festivities. Contestants may enter the sweepstakes, called "The Ultimate Mother and Daughter Mediterranean Escape," by visiting www.princess.com/mothersdayescape.