if($fieldName == 'custom_startselect'){
                if (!empty($_POST['custom_startselect']['custom_hourselect'])) {
                    Do stuff
            // if this is just an "else" I got an unexpected "elseif" on the next elseif line
                       }elseif (empty($_POST['custom_startselect']['custom_hourselect']))  {
                        delete_post_meta($post_id, $fieldName);
               }

            //check for another known grouped input field
            }elseif ($fieldName == 'custom_endselect') {
                           Do Stuff

              //check to see if there is a value posted for this field
              }elseif(isset($_POST[$field['id']])){
            Do stuff
         }