I have two datasets, let's call them 1 and 2, and I want to layer them on top of each other. Typically I do this by ensuring they have the same grain and are writing to the same fact table, and then load them incrementally in different processing groups. In my current scenario however, dataset 1 can grain to a/b/c, and dataset 2 can only grain to a/b. What's the best way to handle this? I'm trying to avoid a union if possible :) Thanks!