How can we update Payment method Bank Accounts Details in One time external payment request

We have OIC integration which reads external payment request file (FBDI formatted .csv) and creates one time Payment Requests. Interface file does not have the payment method ,Bank Account details so Payment request doesn't populate payment method & Bank Account. Payment Requests were created successfully just the bank payment details were blank (see screenshot attached).

Is there REST API or any other option to update payment method ,Bank Account on those Payment Requests created above. Manually we can update them in Fusion application by opening each payment request, but we are looking for automated batch process to update it.