Question or Problem Statement:
I would like to call Subscription object and then update Amendment custom fields.
https://www.zuora.com/developer/api-reference/#operation/POST_Subscription
https://www.zuora.com/developer/api-reference/#operation/PUT_Subscription
https://www.zuora.com/developer/api-reference/#operation/Object_PUTAmendment
Solution:
REST API Subscription Update call does not support updating Amendment custom fields. You can use Workflow as a workaround. In the workflow, you can add an additional Amendment update call to update that custom field.
Here is also a video for your reference:
https://drive.google.com/file/d/1TnnoCWIHZYdCD9wyu6u1_r07hbqG5yEn/view
