1Heat gas or charcoal grill. Spray 1 (18x18-inch) sheet of heavy-duty foil with cooking spray.
2Arrange scallops, fish pieces and shrimp on foil, placing shrimp on top. Sprinkle with marjoram, lemon peel and white pepper. Drizzle with butter and lemon juice. Bring corners of foil up to center and seal loosely.
3Place packet on grill over medium heat. Cover grill; cook 8 to 10 minutes or until scallops are white and opaque, fish flakes easily with fork and shrimp are pink. Serve seafood mixture over pasta.