Embedded MC missing -- broken association?

I’m creating a big flash project (proj2) that’s got a LOT in common with a previous big flash project (proj1). For proj2, I need to use a lot of the movieclips and images that are in proj1’s library, so I copy them over from proj1’s library to proj2’s library.

Lots of these movieclips are simply constructed in the IDE. I created the movieclip, and inserted images and other movieclips that were also created in the IDE. So to be clear, there’s no issue with linkages or classes or anything like that.

The problem I’m having is this: In proj1, MC1 has mc1 inside it. Both, like I said, are created purely within the IDE.

But although I copy stuff from proj1’s library over to proj2’s library, MAINTAINING the folder structure, MC1 no longer has mc1 inside it in proj2.

This appears to be some type of file association problem? What can I do to fix this problem?

Thanks,
Tim