To make a form field mandatory, just change the visibility to "required" for that form field.Admin Panel > Manage > Forms > Form-Name (e.g. Serial Check) > SSN > Visibility = RequiredTo check if it's unique or was already entered I think you'll need to alter the source code. You can check / validate entries against a validator or use a typeahead list to populate serials to the end user, but I'm not sure if this is really what you want. So I suggest to take a closer look at the form field configuration regarding validator etc.