Several AutoCAD drawings are referenced in my model, all of which use XRefs. One block (let's call it DWG1) which is "Not linked" contains references to many .dwg files that need to be updated and/or replaced. Because the files needing updating are nested in DWG1, I am unable to delete and replace those drawings. Furthermore, I am unable to delete the DWG1 block definition (as it is "Not linked", all options are grayed out except for Select and Refresh). Ideally, I would like to delete any reference to DWG1 in my Rhino model and start fresh with all of my .dwg linked references. How can I do this? Thank you so much!
Solution: I ended up exporting the geometry into a new file and making new references to the DWG files.