I have this repo on my GitHub https://github.com/bortek/EZ-WifiBroadcast which is based on Raspbian OS image plus has additional code developed initially by a person which we call here Creator. The code was then taken as a base and developed a lot further by another person, let's call it Continuer. The code contains 3rd party code taken from some other drivers. Now Continuer has stopped the development and kinda left the project.
Some parts of the code include headers stating copyright (or developed) by Creator and Continuer and that the code is distributed under GPL2 license.
The project has been restarted and is now actively being developed/reworked by several other Contributors as well as via Pull Requests from others who forked the code previously and somehow enhanced it.
Now I am trying to get some structure here and feel like we need to establish the license terms for the code being developed. But I do not know how to proceed. I was first thinking about stamping the code with Apache or MIT license but that would be from stamping time and forward. What will happen to the previous code and what right do we (as a project) have to do with the code. We are not planning any commercial activity out of this, this is done purely on our free time and will.