Simplify the following text for a Grade 7 native English-speaking person.
Original: Her older sisters objected to including Maria in their games and once referred to Maria as their `` stepsister '' because she was so good and never got into trouble , recalled Margaretta Eagar in her own memoirs .
Simplified: They once even called Maria their `` stepsister '' . This was because she was so good and never got into trouble , according to Margaretta Eagar .