How do I move back photos from an external drive (but iPhoto library on Mac hd) to the Mac HD without reimporting all images again in iPhoto?

10-11  Source: Network gathering  Views:0 

The following scenario:
Mac HD: iPhoto Libary
External HD: all photos which are shown in iPhoto
now I want to copy back the photos from the external HD to the mac hd and I want iPhoto to know the new location of all these photos (couple of 10 thounsands)
How do I do that without reimporting all images again into iPhoto
do you have a default "managed" library (the iPhoto preference to "copy imported items to the iPhoto library is in its checked state) or referenced library (you have unchecked that option)
What version of iPhoto?
Do you have Aperature 3.3?
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