Three high-ranking advisors to ousted Orange County Property Appraiser Rick Singh, dismissed by his elected successor Amy Mercado, got “golden parachute” deals from Singh that could net them a combined $318,000 from taxpayers, according to a lawsuit filed Monday by Mercado seeking to void the extraordinary severance packages. Singh signed the special agreements for the trio on Sept. 30, about six weeks after he was trounced by Mercado in the Democratic primary. Mercado learned about the unusual severance arrangements after she reorganized the Property Appraiser’s office and eliminated high-paying posts held by Tatsiana Sokolava, Singh’s former campaign consultant who became his chief operational officer; Barbara Jubran, Singh’s human resources manager; and Robert Grimaldi, his legal advisor.