Simplify the following text for a Grade 12 native English-speaking person.
Original: Maggie Grace , who portrays Shannon Rutherford , Boone 's stepsister , was asked to return at the beginning of the season , but Grace was unable due to her schedule ; though she eventually did make an appearance in one episode .
Simplified: Maggie Grace , who portrays Shannon Rutherford , Boone 's stepsister , was asked to return at the beginning of the season , but Grace was unable due to her schedule ; she appeared later in the season , instead .