When attaching a nested reference file but need to edit one particular file in the nested reference. Setting which allows the ability to detach the parent reference while leaving the child reference in place
Make Direct Attachment
Tools > Make Direct Attachment
When ‘Make Direct Attachment’ is applied to a nested attachment in a Master file, it can be modified. The nested attachment becomes redundant with the newly created direct attachment. Quotation marks under Display, Snap, and Locate indicate a redundant attachment.
Key-in: REFERENCE MAKEDIRECT