Ok, so before anyone mentions Ctrl L let me tell you what I am trying to do.
I have imported an fbx file with 100s of chairs in to blender, my client wants me to replace the chairs with a paticular type of chair.
The image attached shows the existing fbx geometry in green, the chair in the blue circle is linked from an external blender file. I would like to replace all the charis in the green circle with the linked chair.
Surely this is possible?