Locking and Breaking External References
You can lock, unlock, or break the external references of components or features created in the context of an assembly and the external references of various types of derived parts.
When you lock the external references on a feature, the existing references do not update and you cannot add references to that feature.
After you unlock the external references, you can add references or edit existing references.
When you break the external references, the existing external references do not update and cannot be restored. You can add references to the component. You can replace broken sketch relations with sketch relations that do not reference the assembly.
You can select the top-level assembly or a subassembly and list all components within its hierarchy that contain external references. Individual references are not listed. You can lock, unlock, or break external references for all components listed or for selected components.
You can select a single item and list its external references. You can lock, unlock, or break all the references at the same time.
You can break, unlock, or lock external references by using dynamic reference visualization in the FeatureManager design tree. See Viewing Feature Relationships.
To lock, unlock, or break external references in the External References dialog box: