About Merging Components
Use Merge to add or subtract a copy of the material of one part to or from another part, after they have been placed in an assembly. By default, when merge is performed a copy of the material is added from the source part into a target part. If the remove material option is used, the geometry of the source part is subtracted from a target part.
When the parts being merged have different accuracies, a message is displayed indicating the accuracy of the target part (up to a maximum of six decimal places). To undo or remove merges or cutouts, delete the merge/cutout features from the source part.
If you merge parts using Merge, mirroring geometry, or adding assembly features, the system does not show the geometric tolerances attached to the merged model dimensions in Drawing mode.
When you Merge material from one part to another, all copied items (surfaces, edges, annotations, entities, etc.) are put on a layer with the same name as the layer they are on in the source part. If the layer does not exist in the target part, it is created. The Hidden status of the layer is copied as well. Features are not copied, but when the feature is on a layer in the source part, all items belonging to the feature that are copied are put on this layer.