Hi, this is the type of project that I really like to do and I have experience with. I propose to create a .NET application that watches that monitors the folder for .XML files, if necessary validate them against an XML Schema to ensure they are suitable candidates for modificaton, and,if necessary, copy them to the new location, adding a timestamp to the filename.
The configuration could be done in a JSON file or a .config file, depending on your preference. The application can be made as a windows service or a window tray application, again depending on what you want.
Can you specify the changes required to the XML>