How can I specify account currency on the supplier bank account and still make payments to that acco

I have a case where the supplier has a bank account in NZD currency but bills the company in AUD. I have the supplier bank account created having NZD as the account currency and this account is assigned to the AUD supplier site however when I enter an invoice in AUD, Oracle does not allow me to select the NZD bank account. If I remove the bank account currency from the supplier account then it is available to be selected on the invoice. The same supplier also bills us in NZD(different OU but using the same bank account). Allow international