How many listeners are too many observer pattern?

My class were inheriting from two Listeners already. And I need to add one more listener. It became something like below:

class DatabaseManager : public DatabaseChangeListener, 
                        public PropertyChangeListener,
                        public RenumberListener

Should I avoid too many observers? Even though listeners are abstract classes it bothers me a bit that I am using multiple inheritance. I am curious has any one had experienced something like; because too many observers code became complex and buggy ?