How to append contact-property to an existing form using the API

[rikotech]

Hello all,

I am new to hubspot. In fact this is my first post.
Although the documentation is quite decent for the HS Api, I couldn't understand how to add an existing contact-property to a HS-form using the API. I read this https://developers.hubspot.com/docs/methods/forms/v2/update_form several times but I am still not sure how to use it or wether this is the API I need to the the job.

Using the UI for this task i trivial, but I want to automate such procedures.

What I don't understand? For example:
in the table "Required Parameters" is described that some fields might be used in the request body, although the do not correspond to any of the JSON file (the example at the right)

I could play with it, but I am afraid that if I specify only one field (the one to be appended to the form) the other fields might get deleted. Not sure.

[WendyGoh]

Hi @rikotech,

Currently, it is not possible to append form field when using the Update an existing form | Forms API. Any form fields added under the fields array would override the existing fields that you already have on your form. 

If you'd like to play around with it, I'd suggest for you to create a testing form for it.