I know that POI only supports XSD of 2007 but CommentsExtended.xml & CommentsExtensible.xml were introduced in 2012. But I need to add this functionality in POI & use it in our end. I have downloded XSD for both these files. But don't know where to get started. I know in general that POI uses Xmlbeans to generate low level classes for XSD Schemas. But don't know where to start & how to proceed. Any help will be really appreciable.

First Attempt

At first glance I tried adding creating CommentsExtended.xml package & add relation to it using OPCPackage API and was successful. But issue seems to be that a new relationship file like commentsExtended.xml.rels is created instead I want to add entry for commentsExtended.xml in already existing document.xml.rels. What am I doing wrong ? How to add realtion for commentsExtended file in the document.xml.rels itself ?