OK, here is my setup, i will then explain what im trying to achieve:
I have a content type of DELIVERY another content type of BOOK and another content type of FEEDBACK
Now, any given user can have anywhere from 1 to 12 DELIVERY content types created (these are created using Rules automatically when they sign up). I use the Node Reference field to attach a BOOK to the DELIVERY content type, if the user has more than 1 delivery content, i will be attaching different books to each delivery content each month. When i attach a book to the users delivery, they can then create a FEEDBACK content to leave feedback under that particular DELIVERY.
So for example,
User 1 - Delivery 1 - Book 1 - Book 2 - Deliver 2 - Book 3
I want the user to be able to create a Feedback content and select the relevant book that the feedback belongs to and once saved it should appear under the particular delivery content.
How can I achieve this?