Development of Creative Commons licenses

[mitro <ml AT somecode.com>]

Hello from France,

Here is the scenario:

- I create a CMS (Content Management System), a set of php script which is 
used
to set up quickly a website.
- I choose the licence CC by-nc-sa for my work
- Some people help me working on my CMS, adding some code, patches, graphics,
etc.

Questions:
- Who is considered as 'author' of the CMS ?
--> me, because I am the one who create the project ?
--> every people who did some work on the project ?

- What happen if someone ask me to earn money using the CMS (someone wants to
sell a internet site which uses the CMS to an enterprise) ?
--> Can I authorize if I want without ask other developpers, or I must ask the
whole team of developpers if they agree ?

- What happen if I want to change my licence ?
--> Can I change it myself or I must ask the whole team of developpers ?

It sounds strange if the author is the only who can decide to authorize
commercial use, change licence, etc.

Thanks a lot for your answers.