Take this with a grain of salt. If you can prove that you project can work without the GPL V2/V3 code being present (eg... the GPL code isn't a major contributi

Take this with a grain of salt. If you can prove that you project can work without the GPL V2/V3 code being present (eg... the GPL code isn't a major contributing factor in the working of your program) then it stands that under copyright law (Here in Australia) that it isn't a Derivative work and thus not infringing on the copyright owner. Playing it safe GPL V2, give credit to the source code in your credits page and push back any changes you've made to their original source. GPL V3, you're kind of screwed (even linking) that you need to adhere to their license agreement and have your source code open source. Personally for open source projects I use GPL V3, and leave a comment in the license agreement the business can contact me for a difference license that comes with support contract.