I'm not exactly clear what it is you're trying to say, but congratulations on the blue checkmark.
Having said that - Both are at fault.
The stepmother offered a somewhat clumsy effort to make nice with her husband's daughter, after the daughter had told step mom she wasn't interested in any association. The stepmom is pushy and unrealistic expecting her husband's kids to accept her and her kids as "family" it doesn't work that way under the best of circumstances.
Stepdaughter is not acting like a grownup. She acts more like the small child shrieking "You're not my mom!" Ten years is way too long to be resentful about your parents' divorce. She could have kept her opinion of the stepmom to herself and made excuses about the play dates. That's what polite and civilized people do, until maybe the stepmom gets a clue or gives up.