Meanwhile, heat oil in large deep skillet on medium heat. Add onions; cook 3 to 5 min. or until softened, stirring frequently and adding garlic for the last minute. Add shrimp and scallops; stir. Cook 2 to 3 min. or until shrimp turn pink and scallops are opaque, stirring frequently. Stir in pasta sauce; simmer on medium-low heat 3 to 5 min. or until heated through, stirring frequently.