Link Library merging objects for final export


I’m designing a level in Blender for use in Unity 3D.

I’ve created a library of some objects, like certain wall units and things, and I link these into my main file with the File/Link option (Groups), so that I can edit them separately, and then link in lots of them into my main file.

That all works fine.

Now I’m in my final stages to export into Unity.

Normally, before I learned to use Link, I would have all my objects duplicated within the file as separate objects, and the final stage I do a CTRL-J to merge all the objects, so that Unity has just 1 mesh to deal with, and also do a ‘Remove Doubles’ to join any close vertices for optimization.

However, I cant seem for the life of me to be able to do this with the linked objects.

I think I have to ‘make local’ dont I, first, on all the linked objects? But even though that makes them all local, I still cant join them, or edit the objects.

What is it I’m doing wrong, and how do I get my linked objects in a state where I can join them all up into 1 mesh?

Thanks for any help,

Rob D.