How to override an app in Django properly?
What I have done which works is to copy the application that I have changed. In this case satchmo\apps\product. 
I copied the app into my project folder
Amended my setting.py INSTALLED_APPS from 'product', to 'myproject.product',
This now carries the changes I've made to this app for this project only and leaves the original product app untouched and still able to be read normally from other projects.
I'm running Satchmo. There are many apps and I've changed some of the source in the Product app. 
So my question is how can I override this properly because the change is site specific. Do I have to copy over the whole Satchmo framework and put it into my project or can I just copy one of the apps out and place it in say Satchmo>App>Products? (Kinda like with templates)
Thanks