Hmmm. I was already having the heroine contemplating how her stepsisters were in fact prettier than she was, though one's a bit silly and the other has tendencies toward pedantry. Their parents could have married when she was old enough that the comparison was likely to stick because they were already nearly grown. Then she could have gone to school before the stepmother insisted on tutoring.
The big difference between this and the last novella, thus far, is that the characters are showing up with more backstory. The sort that stepped back and starting the story there would be tedious, even if it fit the story structure in other ways. But it all has to be slithered in as needed or amusing.