(Paid on Paid or Paid on Billed commission types ONLY)
When paying an advance to a salesperson use the order# as the Advance Invoice#. By doing so it will automatically apply the orders commission to the advance once the order is invoiced. If you overpaid the salesperson with the advance, it would show as negative commission you can then apply to another commission record.
For a Paid on Paid salesperson, it will not show paid in full until customer pays.