Teenage Step Daughter....

So recently my fiancee 15 year old daughter moved in with us. I love the girl,however she is VERY spoiled. Whatever she wants she gets,if not from daddy but from pappy or grandma. She is in cyber school, which we are changing next year. Therefore she's home for a good part of the day....at this age I would expect her to do some chores without me ALWAYS having to say please do this is that before I go to work. Guess I was wrong. I mentioned it to the SO and he told me to get off her back that she isn't a maid , what the hell! I honestly don't believe I'm wrong. I'm glad she's here and I am glad when she dose something without me telling her too. However, I don't believe that I should be bowtowing to her ways I'm supposed to be the woman of the house,but it feels as though I have to watch what I say or how I say it because dad will jump down my throat...