Unable to Update Attribute1 in Supplier Bank Using SupplierBankAccountImport Template / REST API

Summary:

We are unable to update Attribute1 in the Supplier Bank Account record using the SupplierBankAccountImport (FBDI) template or the REST API.

Content (please ensure you mask any confidential information):

We are using below REST but cant see any child link for DFF> 

REST API and response- 

https://{{pod}}/fscmRestApi/resources/11.13.18.05/externalBankAccounts/xxxx

Version (include the version you are using, if applicable):

25c

Code Snippet (add any code snippets that support your topic, if applicable):