Seeking Creative-Commons-like license with addition(s) to request or require modifications be contributed back to source [duplicate]

Question

Do any licenses exist that might serve the purposes below? If not, what licenses might be similarly useful?

Initial license goals

"Drive updates back to the source." My team seeks Creative-Commons-like (...we think?) license with addition(s) to either 1) strongly request or 2) require that modifications of original work be contributed back to the source content (eg: a github.com repo in the form of a pull request).

Enforceability. We do not expect these terms to enable any meaningful form enforceability for those who do not honor the license or "request." Rather, we simply seek to clearly state out intent and preference to more-honorable users and contributors.

Non-sensitive content. We have no concern for loss of rogue-editors source-documentation updates that are not contributed back other than the opportunity cost of the stakeholder community not benefiting from those updates. eg: there's no sensitive content or trade secrets contained in the content. We're simply (mostly) attempting to repackage general community knowledge in a more-efficient presentation.

Main application. For the initial, targeted project we want to create and foster creation of freely-accessible and freely-distributable documentation--and probably not software. At risk of being a bit repetitive: in the license for said application we want to encourage and/or motivate editors to contribute changes back to source repo so that all community stakeholders can benefit over time.

Our team's background

We are not (yet) well-studied in open-source licenses or the depths of difficult legal contracts. As such, please do not let our above "Creative-Commons-like" suggestion deter you from suggesting a significantly-different (from Creative-Commons-like) path.

Answer 1

Requiring people to contribute their changes back to the original project is a bit of a problem point for licenses.

• For open-source license, such a requirement fails the "desert island test" and prevent the license from being an open-source license. The desert island test means that a group of people on a desert island with no way of contacting the outside world must be able to make and distribute changes among themselves without violating the license.
• If I were to receive the software/documentation from a third-party, how would I know where to send my changes? Would that location still be valid in 10 years time? What if the original project stopped in the mean time?

If your main concern is that you can practically and legally incorporate modifications made by others into the original project, then I would recommend you use a copyleft or a share-alike license. These license require that modifications, if they get published, get published under the same license. That gives you the right to incorporate the modifications in the original project, even if they were not explicitly sent to you.
For documentation, the CC BY-SA license would be a good option. For software that license is not recommended and then the GPL or LGPL is a common choice.

Additionally, you can mention in the project's documentation, for example in a readme file, that contributions are greatly appreciated and how they can be made.