private function addJoin(ApiInterface $entity, $alias, $forceFind) {
        if(in_array($alias, $entity->getParentRelationships())) {
            $referencedModel = $entity->addJoin($this->getCriteriaHelper(), $alias);
            return new $referencedModel();
        } else {
            if($forceFind) {
                throw new Exception('Could Not Find Part in current entity: ' . $alias, 400);
            }
            return false;
        }
    }