Problem of using extended collaboration space

Hello
While studying user support, I found some interesting information: https://help.3ds.com/2024x/french/dsdoc/EXP3DBasicsUserMap/exp3dconcept-c-collaborative-spaces.htm?contextscope=cloud#c-securitycontexts
But when I run tests, I don't get what I expect from this reading.

Here is my organization

I'm having a problem with the extended collaboration I use for assessments and for small-group work.

User group members have restricted author rights because they don't need to exchange information between sister organizations.

On the other hand, they do not have implicit readership of the parent organization's content.

What's more, they have no access to :

  • Tto my general (active) library, in which I have classes with standard CAM data (machine, tools, tool holders). This data is in a standard (i.e. public) family collabspace, so it should be accessible since it's public content.

  • In the parts catalog I've created, everything is also in the standard family collabspace

Here are the settings in Collaborative Spaces Configuration Cente

Normally, I shouldn't have to share public data or give public reader rights to data in the STANDARD collabspace...!!!
 

I'm really annoyed because for access to CAM data, I've found the trick of putting the USGs in the public reader on the STANDARD collabspace, but as a result, this identification info is available in the identification information and the students start working in this context and can't save their work.

Is there something I've done wrong?

If I set the USG... to Author, they then have access to the content of other DSGMP organizations via the 3DSpace app, so they can open a colleague's work and duplicate it to make it their own! 
And they still don't have access to the library and catalog!
This is really problematic !!!!

Can you help me ?