How can I apply a modifier to a multi-user data object? I made a scene with a lot of instance objects (Alt+D) and when I press 'Apply' to the  Displace modifier, it doesn't let me.

Is there any way to make it work? Or make the animation of the Displace modifier be still?

I was thinking on copying one, keep the parameter, then deleting the modifier on the instances and then link the instanced object modifier but...it still doesn't work.
Or maybe an option to make the objects as separate in order to apply the modifier?
I need to apply it because it's animated, and I need it still.
You can create a plain duplicate using ShiftD (instead of a Linked Duplicate).

Then apply the modifier on the duplicate. Now this unique mesh data will have the modifier applied to it.

After that, for any object that you want to use the modified mesh, just go to the Mesh Context and select it from the drop-down list.



In this example 'Cube.001' is the mesh with the modifier applied.