Preheat oven to 400°.
Pierce potatoes with a fork; bake at 400° for 1 hour or until tender. Cool slightly. Cut each potato in half lengthwise; scoop out pulp into a large bowl, leaving a 1/4-inch-thick shell. Mash pulp with a potato masher. Add milk and cream cheese to mashed potato; stir with a whisk. Add feta cheese, oregano, salt, and pepper; stir well. Spoon potato mixture into shells. Place on a baking sheet; bake at 400° for 15 minutes or until thoroughly heated. Sprinkle each serving with 1 1/2 teaspoons green onions; top with bacon.