What kind of things does your daughter see her stepfather do for her??? For example, when the family goes out for dinner and Dad lets he ladies out at the crub so they dont freeze in the cold, or if dad is frequently picking her up from after school events, small things she may take for granted..
If she refuses to change and not listen, take thing away from her, the most important ones that he proves, if he pays phone bill or cell phone GONE!!!!! All kids will rebel, but if she lives under the same house as you and her stepfather, in my home, she wouldnt see ddaylight till she worte a appolgy letter. And made a 150% turn around. I think a few weeks amybe a month of tough love 'grouding her from the things she loves most, Ipod, Mp 3 Play station, TV no friends...
I have two girls of my own, the disrespect must be dealt with or it will keep getting worse. Could there be a source to her disrespecr?? Someone asking her things and her drawing conclusions, or someone telling her. I agree with the other comments YOU should punish your child, even though he is at home first, that role is just as important as yours...
I think maybe sittig her down you and her and trying to explain that while your working, stepdad is in charge and, he is a friend, you have a dad, but there nothig wrong with two men loving you and wanting the best for there daughter.