About External Copy Geometry
The external Copy Geometry functionality copies geometry from model to model without copying the geometry in the context of the assembly. Dependency on the assembly and all models along the path between the two components is avoided. When a Copy Geometry feature is created in Part mode, it is automatically defined as external. Source and target components must be relatively positioned, but are independent of the assembly context.
When assembly components are assembled using the same coordinate system, you can use the Coord Sys location option to copy geometry from one component to another. When all the components are assembled, the copied geometry of the target models is coincident to the referenced geometry of the external model.
Components can be deleted from the assembly without losing copied geometry associativity of copied geometry (which happens with internal Copy Geometry features when the target component model is deleted). In addition, none of the other external Copy Geometry features that reference the component will fail.
Although the models are associative to each other through the external copy geometry features, the components are completely independent. In other words, associativity is not controlled by the assembly model.
An independent external Copy Geometry feature remains frozen in its original state, whether or not its external reference model is in session and its geometry has been updated. It does not fail when copied references are missing from the parent model.
If the external reference model is an assembly, all the geometric references must be chosen from the same model. The first selection determines which model this will be. If the first reference is selected from geometry (an assembly surface, datum, and so forth) of the top-level assembly, all subsequent references must be from top-level assembly geometry. If the first reference is chosen from an assembly component model, all subsequent reference selections must be made from that model.