For crust: mix flour, pecans and margarine. Press into 9x13 pan and bake at 350 for 15-20 minutes. For filling: Cream pkg of cream cheese adding powdered sugar. In another bowl, mix 2 envelopes Dream whip according to direction on box. Fold in cream cheese mixture. Spread on cooled crust. Top with Blueberry Pie Filling. Chill.