You cannot change the license on someone else's copyrighted work. > Windows for example used to ship BSD licensed code, and it would have been a violation of W

You cannot change the license on someone else's copyrighted work. > Windows for example used to ship BSD licensed code, and it would have been a violation of Windows' license to modify that code (even though the original code was under a free software license). Microsoft didn't include source and if I had obtained the BSD licensed source, I could certainly modify it and distribute it (but not the code written by Microsoft). Also, the BSD doesn't have a sublicense clause which is problematic for your first sentence.