Your first interpretation is closest to my thoughts. This quote interests me: "For her own gratification she could have wished that something might be acted, for she had never seen even half a play, but every thing of higher consequence was against it." Perhaps without her quite knowing it, her desire to see something acted begins to chip at her disapproval of the scheme. She has taste and loves to read and be read to, and we see later, when Henry reads to their family party, that her taste does sometimes override her conscientious objections.
To take it a bit further, I see this part of the novel also as a commentary on the education of young women in Fanny's situation - taught to obey their superiors in every particular. Supposing Fanny were made of moral steel and steadfastly refused to take part in anything to do with the play, as Edmund did at first, what would her life have been like? Mrs. Norris in particular would never have stopped hounding her, talking about how ungrateful she was to stand in the way of her dear cousins' pleasure, and what better did she have to do during the day anyhow, as it was quite scandalous that a girl in Fanny's situation should sit idle while everyone else was working their fingers to the bone, and what would dear Sir Thomas think if he could see how sulky and ungenerous Fanny was acting, and how fortunate Fanny was to be in a position where she would be able to have the pleasure of a play without having contributed any of the work to it!
Her willingness to run lines seems to depend on the person. For some, she's simply used to being used in that way. For Rushworth, she feels pity for him, as well as a hint of fellow-feeling, watching a loved one fall for a flashy Crawford. Mary, of course, is a more complicated case, but despite her faults, she is kind to Fanny, and not always just to get Edmund's attention, for which Fanny is grateful.
When the crucial moment comes, and Tom asks Fanny to play Cottager's Wife, they all press her to do it. And then her only support in this immoral scheme crumbles, and Edmund chimes in. Poor Fanny's education wins out over her better judgment. She gives in. Her education has not prepared her to encounter the pressures of the sinful world. She has been taught by the adults in her life that to do right is to comply and submit, not to stand firm.
To take it a bit further, I see this part of the novel also as a commentary on the education of young women in Fanny's situation - taught to obey their superiors in every particular. Supposing Fanny were made of moral steel and steadfastly refused to take part in anything to do with the play, as Edmund did at first, what would her life have been like? Mrs. Norris in particular would never have stopped hounding her, talking about how ungrateful she was to stand in the way of her dear cousins' pleasure, and what better did she have to do during the day anyhow, as it was quite scandalous that a girl in Fanny's situation should sit idle while everyone else was working their fingers to the bone, and what would dear Sir Thomas think if he could see how sulky and ungenerous Fanny was acting, and how fortunate Fanny was to be in a position where she would be able to have the pleasure of a play without having contributed any of the work to it!
Her willingness to run lines seems to depend on the person. For some, she's simply used to being used in that way. For Rushworth, she feels pity for him, as well as a hint of fellow-feeling, watching a loved one fall for a flashy Crawford. Mary, of course, is a more complicated case, but despite her faults, she is kind to Fanny, and not always just to get Edmund's attention, for which Fanny is grateful.
When the crucial moment comes, and Tom asks Fanny to play Cottager's Wife, they all press her to do it. And then her only support in this immoral scheme crumbles, and Edmund chimes in. Poor Fanny's education wins out over her better judgment. She gives in. Her education has not prepared her to encounter the pressures of the sinful world. She has been taught by the adults in her life that to do right is to comply and submit, not to stand firm.