Error REST-API attribute Payee Site is required, but invoice type "Payment request" employee

Content

Employees use Expense to launch their expense reports.

Some of these expense reports will not be paid directly to the employee, but another payee, who will pass this payment on to the employee.

Then, when integrating the expense report with the AP, we created a standard invoice for this other payee, linking the employee's expense report to the invoice via a descriptive flexfield.

We will use the invoice validation event in the OIC to create this invoice automatically.

But when paying this created invoice, we want to pay the "Payment request" that generated this invoice.

For that, we would use the event payment in the OIC, and use this REST-API (fscmRestApi/resources/11.13.18.05/payablesPayments) to pay for these "Payment requests".