Hi @bayareawebpro
ACF PRO serializes all the form data into 1 hidden input which prevents the ability to modify such data. This is a security measure which is now hindering your functionality.
Looking at the acf_form_head() function found in api/api-template.php, you can see that the form data is posted via $_POST['_acf_form'].
An easy solution would be to use PHP BEFORE the acf_form_head call, and modify the $_POST['_acf_form']['return'] data. You will not be able to do this with JS alone, but can do it all with PHP.
Hope that helps.
