Prepayment Made to One Supplier but goods (partly) delivered by another Supplier

Scenario:

Company has paid a prepayment of USD 1000 to Supplier X for goods. But Supplier X mentioned they can delivery only goods worth USD 700 and for the remaining USD 300, get the goods from Supplier Y. Supplier X directly paid the left over amount of USD 300 to Supplier Y.

Now how to handle the below,

1. Left over balance in Prepayment Amount Paid to Supplier X

2. Supplier Y Invoice Settlement in the System.

Regards

Uday