Referenced drawings can be edited by opening them directly, or you can edit the xref in place from within the current drawing. You can edit a block definition directly from any selected block reference.
The simplest and most direct method for editing xrefs is to open the referenced drawing file in a separate window. This method gives you access to all objects in the referenced drawing.
You can modify external references and redefine block definitions from within the current drawing by using in-place reference editing. Both blocks and xrefs are considered references.
To edit a referenced drawing from within the current drawing, you use the working set to identify objects that belong to the xref or block definition rather than the current drawing.
While editing a referenced drawing or a block definition in place, you can save back or discard changes.
There are limitations with editing referenced drawings and blocks from your current drawing if they contain nested objects.