For example if I call my friend. I know he is wether with his brother or sister, and then I ask further: Are you together with your brother or...
you can finish the question in several ways:
... together with your sister? ... with your sister? ... your sister? ... sister?
Maybe some of the options sound somewhat strange, but they are all acceptable, and they are equal in meaning.
Is there any universal cross-linguistical preference for which place to go further (e.g. one word class is more preferred than another)? To what extent is the phenomenon language specific? Is there any pragmatic or stylistic difference in them?