Use the structure catalog to browse through external files and view the mechanical structure definitions of that file.
You can drag component views and folders on to model space to insert them as xrefs.
When you drag an external component view on to a drawing, you insert it as a new component instance. The new instance is nested directly below the root node of the mechanical browser. To nest it below an assembly, activate the component view you want to nest it under, prior to dragging the external component.
When you drag a component view on to a drawing, you have a new component instance with one component view. You can right-click the component in the browser and insert the remaining views.
When you insert an xref component or folder into a drawing, the source drawing is attached as a referenced file. The Current Drawing tab of the structure catalog shows the referenced files and provides you with the capability to manage them.