Payee Bank Master Control Account, Unique Number

Hello, Am trying to understand what's the best way to place and print Payee's bank master account and associated unique number.

This is specific requirement for one of the bank where it's required to pay using one unique number associate with master account number. I have to print this information in payment format output file as below.

For example:

Account Number:XXX098989  Amount: $1.00 Unique Number: ABC12345

I know that I can create payee external bank account for supplier and enter the details of Bank, Account number, but where can I enter this unique number so that I can retrieve..

Thank you...