OTV Alphanumeric bank accounts in BSEC-BANKN

Hi

We need to make payments to FX bank accounts that are alphanumeric.  ie.  12 3456USD123456

SAP allows this format in normal vendor masterdata which populates LFBK-BANKN, however if you enter a one time vendor invoice, table BSEC-BANKN is populated which does not allow alphanumeric bank accounts.   Error = AR124

Any suggestions how to get around this?