protected function addOwners(array $owners)
    {
        foreach ($owners as $owner) {
            if (isset($this->modelPopulators[$owner])) {
                continue;
            }

            $modelPopulator = new ModelPopulator($this, new $owner, $this->generator, [], []);

            // We'll add the owners in reverse order, so that the children will be associated to their parents.
            $this->addOwners($modelPopulator->getOwners());

            $this->modelPopulators[$owner] = $modelPopulator;
            $this->quantities[$owner] = 1;
        }
    }