The customer would prefer to reuse the original voucher number for the deferred revenue posting (must be a parameter setting that complies to the ledger parameter “allow duplicates”). Since it is not possible from the UI to specify “Default description” it is not possible to modify the description in order to use this for settlement purpose.

Another suggestion could be to “populate” the invoice number to the GL journal for the deferred transaction to “Document” field, since our invoices includes the invoice number in document – I can see this information in the settlement form so the customer can easily match transactions via "document"