Old version name after external edit.

I know Aperture inside out but cannot work this one out.

As part of my work flow I rename my files using the batch change under Metadata and apply it to the masters. They are all residing in the Aperture lib. All my files have new version names, and the master file name has changed with the .cr2 file extension.

Then when I do an external edit on the images either using photoshop of one of my external editing programs, Aperture creates the working tiff but with the original file name it had at import. Where does it get this from once they have all been updated. Is there somewhere where this can be changed. I seached preferences inside out. My work around is to go to the master in the stack and in the metadata pane copy the file name and then go to the working tiff and selcted the old file name and paste over it adding -V2.

Where does it get the old file name from and where can this be changed ?