Customer PO at item level needs to be populated to existing Z report

Question

Hi All,
Just would like your confirmation on the below requirement.
Requirement: Already there is existing Z open sales orders report is availble for which we need to add the below mentioned line item PO into the output of the report.Business manually change the line item PO that should be displyed into output of the report.
And one more point already the header PO  number is alredy displying inth output of the report.
My understanding is: Since the customer PO is unique to the entire document what ever the PO is maintained at header level which will be copied to all the line items, even i checked the line item and header table & field both are same VBKD-BSTKD hence eventhough user manually change the Line item PO number you can't get the same into the output the of the report is this my understanding is correct or we can display the line item PO details into output of the report?
thanks,

Answer 1

Thank you DB49 for your above answer,also checked with business why they want to maintain the line item wise the PO details.
The answer is recently they have implemented high sea sales process during the Post go live they could not complete the total cycle thorugh SAP, only sales order created in SAP but not Vendor invoice and customer invoice etc were manged manually.
In sales order it contains more than one line items. Business has compelted upto customer invoice for some line items( sales order in SAP and remaining through manual).
So now when the user is trying to pull the open sales order report system is pulliing the above compelted line items also, sytem is doing correct beacuse in SAP only sales order created and remaining process through manually. But actually the report is wrong.
So now the business will enter manully some description for those line items which is completed until billing ( sales order in SAP+ remaing process through manual). so that in the output of the report they can understand which which are all the line items in sales order are completed the billing.
Hence they want to disply the line item PO into the output the report so i think it makes sense to me now, do you think any other alternative for the above requreiement ?
thanks,