use and install python personal libraries

Question

I have two python projects, one includes useful packages for file manipulation and such. They are usefull because they can be reused in any other kind of project. The second is one of these projects, requiring the use of my useful packages. Here is my projects' file structure:

Python-projects/
  Useful/
    package_parsing/
    package_file_manipulation/
    package_blabla/
  Super-Application/
    pkg1/
      __init__.py
      module1.py
      module2.py
    pkg2/
    setup.py
    MANIFEST.in
    README.rst

First of, I would like to use the Useful/package_parsing package in my module Super-Application/pkg1/module1.py. Is there a more convenient way to do it other than copying the package_parsing in Super-Application project?

Depending in the first answer, that is if there is a way to link a module from a different project, how could I include such external module in a release package of my Super-Application project? I am not sure that making use of install_requires in the setup.py will do.

My main idea here is not to duplicate the Useful/package_parsing package in all of my other development projects, especially when I would like to do modifications to this useful package. I wouldn't like to update all the outdated copies in each project.

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EDIT 1

It appears the first part of my question cna be dealt with appending the path:

import sys
sys.path.insert(0, path/to/Useful/package_parsing)

Moreover I can simply check the available paths using:

for p in sys.path:
    print p

Now for the second part, how could I include such external module in a release package, possibly using the setup.py installation file?