Preheat oven to 350 degrees F (175 degrees C). Grease three 9-inch pie tins.
Mix flour, margarine, and sugar together in a bowl using your hands until mixture is crumbly.
Layer apples and pears in the bottom of the 3 pie tins; sprinkle blackberries over apples and pears. Evenly distribute flour mixture over the fruit mixture.
Bake in the preheated oven until fruit is soft and topping is light brown, about 40 minutes.