There is a simple project licensed under BSD3 that provides a CMake module. The project has a CMake build system that builds an example document by including the provided module. The CMake module has the BSD3 license and copyright included within it, which I assume applies to the entire project, not just that file.
To mesh this project with my own, I have modified the build system. I have captured these changes in a patch file. While the project containing the patch doesn't include the original project, it does contain a few lines of code from the build system inside that patch file as context for my changes.
Since I am relatively new to working with open source licenses, I am wondering what is the appropriate way to mark the project to ensure the terms of the original license are fulfilled. I know I need to include the original copyright, license, and disclaimer, and I would like to release my own code/changes under an equally permissive license (BSD2, BSD3, or MIT), but I am unsure how to differentiate what parts are covered by which license.