That is not available for edit currently, editing the core is never recommended but if you need to then you can find the information in the first function of /users/obits.php
function go_meta(){
global $wpdb;
if ( get_option('permalink_structure') != '' && class_exists('wpfh_premium') ) {
$_GET['id'] = get_query_var('id');
$_GET['f'] = get_query_var('f');
}
if($_GET['id'] !=''){
$r = $wpdb->get_results("SELECT * FROM ".$wpdb->prefix ."wpfh_obits where id = ".$wpdb->escape($_GET['id'])."", ARRAY_A);
if( $r[0]['photo'] == ""){ $r[0]['photo'] =get_option('wpfh_obit_default_pic');}
$name = ''.__("Remembering","sp-wpfh").' ' . stripslashes($r[0]['first_name']) . ' ' . stripslashes($r[0]['middle']) . ' ' . stripslashes($r[0]['last_name']) . ' ' . $maiden . '';
$description = substr(stripslashes(strip_tags($r[0]['obituary'])),0,200);
$obit_page = wpfh_obit_page($_GET['id']);
$image = '' . content_url() . '/plugins/wp-funeral-press/thumbs.php?src=' .get_real_image_path ( $r[0]['photo'] ). '&w=400&h=500';
echo '
<!-- for Twitter -->
<meta name="twitter:card" content="summary" />
<meta name="twitter:title" content="'.$name.'" />
<meta name="twitter:description" content="'.$description.'" />
<meta name="twitter:image" content="'. $image.'" />
<meta property="og:title" content="'.$name.'"/>
<meta property="og:type" content="article"/>
<meta property="og:url" content="'. $obit_page.'"/>
<meta property="og:image" content="'. $image.'" />
<meta property="og:description"
content="'.$description.'"/>';
}
}