AMEX Both Pay Credit Card Program

I have a question regarding setting up a Travel Credit Card Program as both pay.

 

The situation is that an Employee received a credit transaction and it interfaced to iExpense.  The user reconciled the credit transaction and it interfaced to AP.  This was the only transaction that was on the Expense Report.  It created a Mixed Invoice in AP that contained the other positive lines and then this credit line.  The situation is how are clients dealing with issues in which the net pay for a specific card is less than zero.  AMEX does not accept net payments of less than zero.  Currently the client has to manually place the AMEX Invoice on hold but