In a medium saucepan, bring 3 cups of water to a boil. Once boiling, add in the three boxes of grape Jello. Stir well until fully dissolved, about 2-3 minutes.
Remove the saucepan from heat and allow it to cool slightly. Stir in the drained crushed pineapple and blueberry pie filling until well combined.
Pour the Jello mixture into a large mixing bowl and place it in the refrigerator. Let it chill for about 1-2 hours, or until it starts to thicken but is not fully set.
While the Jello is chilling, in a separate bowl, beat the softened cream cheese until smooth. Add in the sour cream, white sugar, and vanilla extract. Mix until everything is well combined and creamy.
Once the Jello is thickened, gently fold the cream cheese mixture into the Jello. Use a spatula to combine carefully, ensuring you maintain the light and airy texture.
Transfer the combined mixture into a 9x13 inch baking dish or your preferred serving dish. Spread it evenly and smooth the top with a spatula. Cover with plastic wrap or a lid and refrigerate for at least 4 hours or overnight to set completely.