fewbricks\acf\fields\repeater::add_brick PHP Method

    public function add_brick($brick)
    {
        $brick->set_is_sub_field(true);
        $brick_settings = $brick->get_settings($this);
        foreach ($brick_settings['fields'] as $brick_field) {
            $this->settings['sub_fields'][] = $brick_field;
        }
        return $this;
    }