I am planning to write some financial modeling software targeting enterprises. It will be based on an existing open-source project that already has a BSD-3 license. I do not own the copyright to the original project but will be using it to create my derivative work. I would like to keep my project open-source as well but I can imagine a situation where a company wants to hire me to make additional modifications or request development of special features specifically for their business. They would likely require such modifications to be closed and proprietary especially if it pertains specifically to their business.
- In that situation, am I allowed to issue a separate license to the client since I am the copyright holder for the derivative work? Is it possible to keep that version of the software closed source?
- If I accept contributions from the open-source community, I assume there would then be other copyright holders to different parts of the software. Do I need to acquire copyright transfer from contributors? Is that even possible with the existing BSD-3 on the original work?