How to add extra subfields

I am trying to add a third party API using the API connecter but I keep getting the 400 bad response. I am using the POST request and have it set as an action. The problem I think I am having is that on the third party API documentation some of the request body schema the “from” (participantinput) has dropdowns with further information like "id " “email” “type” “name” etc. In my API connector I have “from” as a key parameter but given that on the third party api documentation the “from” has a dropdown with further fields so I was wondering do I need to create separate keys for each one or is there a way of incorporating them

into the same “from” key. This is the same issue with the “settlement” it has an array of subsections like “id” “type” etc and I was wondering if I create separate keys for each one as well?

Any help would be much appreciated

When this is a JSON, I prefer to use json directly (instead of parameters)
Copy paste the json example from DOC into the BODY Json field. Replace value by <valuename> and you will see a list of parameters showing under the text box of BODY Json.

Thank you I will give that a try.