Change the behavior if user is allowed to change the annotation (edit comment). This is used in OssnAnnotation->canChange($user_instance); It will check if annotation -> owner_guid is loggedin user GUID OR isAdmin then return true you may override it.

<?php
function my_component_init(){
		ossn_add_hook('user', 'can:change', 'my_component_hook');
}
function my_component_hook($hook, $type, $allowed_or_not, $anObject){
		//$anObject contain OssnAnnotation object
		//allowed_or_not contains true|false
		return $allowed_or_not;
}
ossn_register_callback('ossn', 'init', 'my_component_init');