A family for display
The Banks had another incentive for taking Sam in – they wanted to build a reputation for themselves in the small town. That’s why whenever they were in public, they would shower Sam with love, in a “sick, cotton candy fashion” that made her extremely uncomfortable.
They also forced Kitty to be nice to her step-sister in public, which both girls resented. When they were back in the house, Kitty couldn’t care less about her stepsister.