Swapped At Birth: The Other Family

The scene starts with Harold and Martha Green seeing their friends off after dinner and discussing their daughter Cassie. Martha asks if Cassie is ready for the truth about something big. Harold is uncertain and worries what might happen if she reacts poorly.
He suggests they might need to be firm with her. Days later, the Greens surprise Cassie for her birthday with her older sister Heidi. The family reveals to Cassie that she is not their biological daughter, explaining a swap at birth arrangement with their friends.
Cassie gets angry and storms out, but Heidi soothes her by sharing she was also part of a swap deal. Cassie reluctantly agrees to try giving in to her parents' desires. During a private moment between Cassie and Heidi, they undress each other tenderly as Harold and Martha eagerly watch, getting aroused.
Soon, the whole family will engage in passionate intimacy together.