I'm a new leader to a company and for the company a new department. I'm trying to establish myself as a leader of the department. Before me there was another person in another department managing the day to day and putting out fires in my department.  

My boss who we both report to wants her to move away from the tasks I'm now responsible for, but she keeps setting up meetings to put out fires and making decisions before I get a chance to respond. The rest of the departments look to her for answers on certain things I feel I should be responsible for.  

How should I handle this situation?  

I appreciate her input because I'm new to the company and need her help in putting out fires since I don't know the protocol that well but at the the same time I want to phase out her responsibilities.