Multiple invoice line items in DMEE tree output for Flat file

Hi Experts,

We have developed the custom DMEE tree for our US client to send the payment file in flat file format. As per the bank file specification file if a vendor is having multiple invoices all the invoice details need to be captured in a header records.

We are getting the 1st invoice details only per vendor and rest all invoice details are being missed in the out put payment file.

Any configuration/user exit will help to complete this requirement. Any help on this will be highly appreciated.

Thanks

Vallabh