Copyrigth on custom modules

Hi everyone. I would like to know if you could help me determine what is the criteria to use for the copyright of custom modules. Currently we use the same header for all our python files (the same one used by Tryton modules), and in the COPYRIGHT file we try to place the people we consider according to the modules seen for development, but sometimes this task is confusing. It would be valid to put only something like '2008 - 2020 © Tryton Project (or Foundation
) '?

IMNAL, but that does not sound like a proper way.
You must give the copyright to someone else if you are reusing his code (copy/paste). If you are just reusing the idea, this is not copyrightable.

The Tryton Project is not a legal entity.
The Tryton Foundation up to now did not produce any code.
Also you can not attribute the copyright to someone else without having a CLA signed. This is something we always wanted to avoid for Tryton because it adds extra works (managed signatures, verify it for each contributor etc.) and it is more secure to share the copyright than having a single entity owning everything.