Is it possible during run-time to modify and save an XML file inside a program and not as external file?

I tried to look for an answer to this question but didn't find any, maybe I didn't use the right words, but nothing came up.. maybe it's because it's not possible?

I would like to have an XML file that will be synced with a treeview, and there will be changes made to the treeview which will effect the XML file, then I need to save it, but I can't give the user direct access to this file, so I would want to compile it with the program, the question is, is it possible to modify and save the XML that way?

Thanks a lot!

Ray.