Join the effort
You are welcome to get all the benefits of OpenPetra, and to use the chance to take the project forward. This can happen by contributing to the translations or to the manuals, by helping other people on the support forums, or by actually giving developer time of your own IT staff or hired developers.
This will allow you to customise OpenPetra greatly and add features that you need. By contributing such features back to the project you have the safety of knowing that they will still work with the next release.
Please also ask the supporters of your charity to consider to volunteer with the OpenPetra project, which will benefit you directly or indirectly.