To create a virtual document, you convert a simple document to a virtual document. This document becomes the parent document, to which you can add descendants.
To create a virtual document:
Navigate to the file you want to convert to a virtual document.
Do one of the following, depending on the options available:
Click More>Tools>Convert to Virtual Document.
Check the document’s checkbox. Then select Tools>Virtual Document>Convert to Virtual Document.
Add descendants, as described in Adding a descendant.