How do I change the description of the same image which is to be found in multiple instances?

We have the site from http://ift.tt/1543WG7

Feel free to dig the site in order to understand our question below.

Of course, any feedback appreciated :-) but my main question is the following:

We have a photo multiple times on site (in blog, portfolio, and in slide-shows from the menus Body, Mind, Heart).

The description of the photos is taken from 'Description' field from Media Gallery. (As you know the field is filled from photo's EXIF).

Because each time when I attach a photo to a page/post, WordPress copies the photo, we need a plugin/solution/whatever to allow us to change simultaneously the description of all the instances for the eg. myPhoto.jpg.

Now when we want to change/update a caption, we need to go to all instances and manually edit them.

Does someone knows a solution for this problem?