Globally defines a one-to-many relationship. Once defined, the relationship persists for the life of the script.

class person extends ADOdb_Active_Record{}
ADODB_Active_Record::ClassHasMany('person', 'children','person_id');
 
$person = new person();
$person->Load("id=1");
foreach($person->children as $c) {
    echo " $c->name_first ";
    $c->name_first .= ' K.';
    $c->Save();  ## each child record must be saved individually
}