It is difficult to know all the nuances of this situation because I do not know your stepdaughter’s age. But I’m guessing she is young, and it would make sense that her experiencing all of the rules would be overwhelming.
But it’s important for children to have both love and limits. The research shows that children raised without understanding that there are restrictions in life don’t do as well as those who have encountered this information. Here’s a link to a parent’s site called Say Yes To No. Research is evidence-based and helps parents cope with the necessary limits they must impose on their children (or stepchildren.)