The new functionality to add attachments while bursting is for PDF attachments only and that too only when we hardcode the work order number in the attachment query.
So this new feature is in order to send a common PDF document as attachment along with bursting an output. Due to the incapability of addressing passed parameters in the attachment query, attaching a PDF file based on changing WO numbers is not a part of this feature as per Oracle and would require an enhancement request.
Enhancement Request / Service Request: SR 3-28844384961