Drain oranges, reserving juice in a 2-cup measuring cup; set oranges and juice aside.
In a large bowl, dissolve gelatin in boiling water. Stir in cranberry sauce until melted. Add enough cold water to the reserved juice to measure 1-1/2 cups; add to gelatin mixture. Stir in oranges. Chill until partially set.
Meanwhile, in a large bowl, combine the pretzels, butter and 2 tablespoons sugar substitute. Press into an ungreased 13-in. x 9-in. dish; chill.
In a small bowl, beat cream cheese and remaining sugar substitute until smooth. Fold in whipped topping. Spread over crust. Spoon gelatin mixture over cream cheese layer. Chill for at least 3 hours or until set. Yield: 15 servings.