TrackTo and object linking


I wonder if there is any way to force blender to use TrackTo within linked group to object outside this group?
I.e. I have few objects in group and one of them have TrackTo to empty. It works fine in this blend file. I can parent this empty to i.e. camera and it works fine.
But if I link this group into another file, whole group is static because I can’t move this empty. When I make proxy for this empty TrackTo doesn’t track this proxy.
Any ideas?

You mean something like groups of groups?

No, I just want to set TrackTo empty contraint’s inside group, then link this group into another file and be able to move this empty. Now if I link group then I can’t move the empty, but when I make proxy for this empty constraint don’t work.