I will suggest to have a one-on-one with her

Talk open but politely. Let her know as direct report, you are there to help her and make her life easier (that is part of your job duty). You should also ask for her help, part of her duty is growth of her direct reports. Ask her if she can help identify clearer on your performance goals and responsibilities. Do not take it personally, work is work. Your denial reflects on your way of thinking, talking, words that you pick can be unconfortables and offensive even without self knowning. It is ok not being the one speaks for the group or getting credit. Know a fact, bosses are tie-ed to any credit that his/her direct report earned, as well as faults. So, she is not stealing. Back her up more and gain the trust. At the same time, find ways to learn and grow on other area. If you cant change the fact of being her direct report, accept and work on it. 

Sorry, first timer on this site, and cant type Chinese on my computer at this point.