I know that in Magento 1.4.2.0 one gets parent id's like so
list( $parentId ) = Mage::getModel('catalog/product_type_configurable')
->getParentIdsByChild( $product->getId() );
My question is: if I don't know what the parent is, how do I know to use the 'catalog/product_type_configurable' vs 'catalog/product_type_grouped' model to get the id?