Is it possible to trigger a webform submit via url?
Inject some javascript into the body using PHP can make auto submit to work by a param in URL:

 http://example.com/event_form?autosubmit=yes&amp;option=y


For example, the webform node ID is 101:

&lt;?php if ($_REQUEST['autosubmit']) { ?&gt;

    &lt;script&gt;
    (function ($) {     
        $(document).ready(function(){
            $('form#webform-client-form-101').submit();
        });
    })(jQuery);
    &lt;/script&gt;

&lt;? } ?&gt;