My understanding with most open source licences such as GPL, if you make any changes to the source code in order to better support the software, you're obligate

My understanding with most open source licences such as GPL, if you make any changes to the source code in order to better support the software, you're obligated to share those changes. Other than that you shouldn't have any obligations to the software author(s). Although, it's best to thoroughly read the software license in question and perhaps even consult an attorney competent in software licensing.