Hi. I think this question was already raised a long time ago at SmartBear. See Rest request attachments multipart form data for json file with parameterized json data | SmartBear Community
It has been logged by SmartBear as a enhancement request RIA-22427.
I reached out a few days ago as to when this would be available in ReadyAPI. I got back following response:
We understand your concern. Thank you for getting back to us. I’ve notified the Product team regarding this requirement and have increased the priority of the enhancement request. As you mentioned, this functionality should indeed be available within the product, and I’ll work with the team to ensure it’s considered for implementation at the earliest. Apologies for the inconvenience caused.