How to deal with in-laws and married sister-in-law who always comes to stay with us?

i live in a joint family (in-laws and us), hubby's sister got married recently but she spends more time at our place than to her house. Her parents (my in-laws) encourage her to do so- calling her every other day and asking to come over. How could I deal with it. Me and my hubby run the family (in terms of expenses) we both don't want to be rude to in-laws but at the same time I can't take it any more. It's really painful. Please suggest.