What is the main conflict in Three Plays by Eugene O'Neill?

In the play, Desire Under the Elms, the action is set entirely in and around the farmhouse, which is appropriate because the house is the focus of the conflict between the characters. All of them - father Ephraim, older sons Simeon and Peter, younger son Eben, new wife Abbie - claim ownership of the house for their own reasons, and all go to varying lengths to secure that ownership.