Autofill with user entered content and if the value isn’t there – add it

Hey,

So I am looking for a solution, been sitting on it for couple hours and to no avail, been testing it into multitude of ways but…

The case:

– Book website with user generated content
– Users goes to the front form, where he is able to add an author and a book title
– He starts typing into an Author field and if there is same author name present, he clicks onto it to apply the name
– If there is no Author of same name, he adds a new entry.
– All entries are user generated, so there is no loaded list, except the ones that the users create by adding a new entry.

I have ACF PRO and Formidable Forms PRO, how can I achieve the above? Another option would be to just populate the fields within a dropdown (from user generated authors) and have an option in the dropdown to add new, which would then redirect or show a hidden entry text field.

Would be perfect if no custom coding is required and can all be done by WYSYWIG editor.

Thanks!