In a medium saucepan, combine the salsa, olives, capers and parsley. Bring to a boil over medium-high heat, simmer for several minutes to blend the flavors (and if the salsa is at all watery, to reduce a little of the liquid), then remove from the heat. Cool to room temperature. In a large bowl, combine the shrimp and crab meat. Gently stir in the sauce, then cover and refrigerate until you’re ready to serve.