When you create an Automatic material removal feature, the Intersected Comps dialog box opens to let you specify the level (part, subassembly, or the top-level assembly) at which the feature should be visible. If you click AutoAdd, the volume of material to be removed by the NC sequence will be automatically intersected with all the affected workpieces and the results displayed. If the intersection is performed at the part level (that is, it will be visible in Part mode), and the assembly has several instances of the same part, you will be prompted to select one occurrence of the part to intersect the assembly feature with; then the material removal will be shown on all parts according to the instance selected for intersection.