Saving Sessions and missing fade files

[Kevin01]

I have a PT 002 setup. I have been going through cleaning up my hardrive space and backing up some sessions that I just completed. Here is where my question/problem is: Let's say song X's final mix is done and I want to save it to my back up Hardrive as well as save it to a DVD. Since I have a final mix/finished song, I want to delete all the previous versions that I have. When I go to put the previous versions in the trash and then try and open song X's final mix, it is missing Fade Files ect. and so it will not open properly unless the older version are on the hardrive. So it looks to me as if the final mix of song X needs these previous versions fade files to open. How do I remedy this? How can I avoid this problem in the future? Am I doing something wrong? Can I combine the previous versions fade files into one folder? I hope someone here can help.