When assembly has multiple instances of external model imported, any modifications of particular instance depends upon how it is made ‘Independent’. So when you ‘Make Independent’ the component, the component level operations became independent. But the Independent status is not propagated down through the component. Hence any modifications done on body level will be reflected in all instances. But when you make bodies independent, the status propagates up till component and also any modification done at body level will not reflected on the other instances. Making component independent is useful in file handling and management. Example if you right click on component, most of the operations listed are assembly level. Ex. Rename, Sort, Create a New component, Lock etc. If the component is not “Independent”, it will make the changes in all component instances. If the component is “Independent”, it will make changes to particular component only while still you can see any modification done on the body level affecting all similar bodies in other components as well.