Cosinga Palpatine's mistress

An unidentified woman was the sister of a (presumably conservative) candidate for the Naboo throne and the mistress of Cosinga Palpatine. Before Palpatine, Cosinga's son, murdered his father in 65 BBY, he accused him of wanting to place himself in a position of power by supporting his mistress's brother's bid for the throne.

Behind the scenes
The Dark Empire Sourcebook reveals that Palpatine allegedly had a grand-neice, Ederlathh Pallopides, who was put forward by Admiral Betl Oxtroe as a successor to the Imperial throne at the age of eleven. However, Star Wars: Darth Plagueis reveals that Palpatine killed his entire family, including his at least four siblings, aboard the Palpatine family starship in 65 BBY, and that he inherited all the assets of House Palpatine. Cosinga Palpatine's extramarital affair leaves open the possibility that the Pallopides claim is valid.