Keeping documents assigned to new object when created from an existing object

I have used the property calculator to be able to create a new object from an existing one. However when the new object is created it is assigning the documents from the original object to it . I changed the settings to duplicate = yes and it completely stopped working.

I have set it up that a New Enquiry changes to a Job Pack once the quote is approved. At this point a Job Pack is created where further documents will be added to the job pack but the customer wants all documents when it was at New Enquiry to remain on the Job Pack.