SPAIN She is the heir to the heir of the Spanish throne. Leonor is the oldest daughter of Prince Felipe and Princess Letizia, and as such, second in line behind her father. But also in line, with her upbringing, there has been no special celebration except a small private party consisting mainly of her school friends. The Royal Palace (Palacio de la Zarzuela) has another occasion this week, just two days away on November 2, when Queen Sofía celebrates her 73 birthday. The little princess is very popular, especially with the press, who are careful to avoid over-exposing her in the media. Today, though, is an exception.