@moinluk I would use different workflows depending on where the base version resides, size of documents, ratio of replace vs keep, what to find and what to replace the found with. There are many patterns you can use, so gaining some knowledge of key terms is beneficial. E.g. look for xquery's typeswitch if it is not only strings you will replace since this is an easy intro to create documents without going all XSLT. XQupdate is fine for some usecases etc.