I come across this situation quite often when working with references.
I have a base mesh and want to apply different modifiers on top of clones whilst keeping the editability of the base mesh, so I use clone as reference and stick my modifiers on top of that (array for example)
Now, if I want to create another version, referencing the same base mesh, but with different settings to the array modifier, I have to go back to the base mesh, clone as reference again, and set up a new modifier stack. It would be far more convenient if I could somehow copy the original clone and make it unique only above the reference break-line. I could then alter the modifer stack without it affecting any other instances. Is there any way to do this?
If I copy an instance and then try to make the modifiers unique it makes the whole mesh unique, rather than keeping the instance link to the original mesh.