In the film’s adaptation of Mansfield Park, Fanny’s brother William is eliminated from this version. While he is an integral part of the novel and very crucial to Fanny as a friend and confidant, his absence from the film does not take away from the overall significance of the novel.
The film, however gives Fanny strengths in other ways. In lieu of a brother Fanny is more willing to question the actions of others. She reminds Sir Thomas that had he brought slaves from Antigua that they would no longer be in bondage. And there is defiance in Fanny reply when she returns from Portsmouth and Mrs. Norris asks her how long she is to be at Mansfield Park and Fanny redirects the question back to Mrs. Norris.
Fanny’s only friend (William) other than Edmund seems to be represented as personal strength in Fanny rather than a separate individual.