Substituting frozen fruit for fresh in pie

Frozen fruit can be great in a pie--in fact, as most frozen fruit you buy at the grocery store is flash frozen at peak ripeness, it can be more flavorful than fresh fruit. Of course, local, in-season, ripe fruit is hard to beat, but there's nothing wrong with using frozen.
You will have to adjust the amount of thickener in your pie. For instance, for 5 cups frozen fruit, you should use about 3 tablespoons tapioca starch or arrowroot to thicken your pie. No need to thaw the fruit before baking, but be aware that you'll have to increase your cooking time. I would also blind bake your crust before filling it. Line the pie pan with the dough, line the dough with parchment and fill with pie weights or beans, and bake until set, about 15 to 20 minutes. Remove the weights and parchment and brush the dough with beaten egg yolk. Return to the oven for another 8 minutes or so. Then, add your filling. Hope this helps.