Composite documents, section edit.

Hi I am new to xwiki. I am facing a problem with composite documents. I have created 3 classes and its classsheets with a textarea in each class (classes A, B, C) and I included all the three objects in another class D's template and included the forms . Now if I edit any documents of D class then I am able to change the whole document (the part of A, B, C). But I want to do enable section edit the part of A, B, C separately. (One doubt : Is this the correct way of creating composite document?) How can I do this? (Here I am creating documents of type D and thus I am able to edit a document class D. To edit the section of classsheet B there should be a document present in B, I guess. In my case the document will only be in class D.) Can anyone please guide me the exact way to do this. Thanks, Roopesh