Hi, Is there any way to identify by the return_url if the action was create a new subscription or update_capped_amount. When creating the new charge, we set return_url for the create action. When user updates an existing recurring_charge, we want to redirect him to another page. We have tried to update return_url by PUT request, but seems that it is not supported.
I think your question is related to Billing APIs instead of Subscriptions API? Unfortunately I'm not an expert on billing related questions, I would recommend asking the question in "Shopify APIs and SDKs" board instead.