Accounting Entry Issue in Mixed Invoice

Hi,

We have a prepayment to supplier and the supplier is refunding payment.

Then we entered a mixed invoice with negative value and applied the prepayment to the invoice. After we paid it as a supplier refund. I feel that accounting entry is doubtful

Mixed invoice

Reserve for Encumbrance           Dr

Trade Prepayment                         Cr

Supplier Refund

Cash clearing                         Dr

Trade Payables                              Cr

I am Ok with payment entry.

Thanks