PREHEAT oven to 400°F. Tear off four 15-inch sheets of Reynolds Parchment Paper. Fold each sheet in half and crease it in the center. Unfold.
MIX together olive oil, 1 1/2 teaspoons Greek seasoning and seasoned salt; set aside.
COMBINE feta cheese, olives, garlic and remaining Greek seasoning. To create a pocket, make a long, deep horizontal cut in one side of each chicken breast being careful not to cut all the way through. Stuff 1/4 of cheese mixture into each chicken breast half. Drizzle with 1/4 of olive oil mixture.
FOLD over other half of sheet to enclose ingredients. Starting at top corner, make small overlapping folds down entire length of packet to seal edges together. Twist the last fold several times to make a tight seal. Repeat to make 4 packets. Place parchment packets on large cookie sheet.
BAKE 20 to 25 minutes. Meanwhile, combine tomatoes, onions and basil; refrigerate until ready to serve. Place parchment packets on dinner plates. Carefully cut an "X" in top of each packet to allow steam to escape. Top with tomato relish. Serve immediately.