context: Susan Hayward as Mrs. Sheridan
  Struggling actor William McFly (Cliff Robertson) is hired by wealthy Cecil Fox (Rex Harrison) to play his personal secretary for a practical joke. Pretending to be on his deathbed, Fox invites three former lovers to his Venetian palazzo for a final visit: penniless Princess Dominique (Capucine), fading movie star Merle McGill (Edie Adams), and Texas millionairess Mrs. Lone Star Crockett Sheridan (Susan Hayward). Accompanying Mrs. Sheridan is her spinster nurse, Sarah Watkins (Maggie Smith). By chance, each of the women brings Fox a timepiece as a present.
  The three women warily size each other up. Mrs. Sheridan boldly announces that the others might as well go home, as she is Fox's common-law wife, and they can expect to inherit nothing. However, when Sarah returns from a late-night date with McFly, she finds her employer dead of an overdose of sleeping pills, an apparent suicide. Police Inspector Rizzi (Adolfo Celi) investigates.
  Sarah knows that the pills Mrs. Sheridan had been taking are harmless fakes. McFly has already revealed to Sarah that Fox is perpetrating a charade, and that the final joke is to be the reading of the will, empowering McFly to choose the heir. She therefore suspects him not only of being the murderer, but also plotting to kill Fox. When she confronts McFly, he locks her in her room, telling her it is for her own safety. She manages to escape via a dumbwaiter and warns Fox. However, his displeased reaction puzzles her. He sends her back to her room.
  The next morning, Fox is found dead. McFly reveals that Fox was the killer of Sarah's employer. He was broke and wanted Mrs. Sheridan's fortune. Once McFly had figured it out (and more importantly, told Sarah), Fox realized it was all up and committed suicide.
  Sarah asks McFly to write her name down in the will as the heir of Fox's worthless estate as a souvenir, with Rizzi signing as a witness. After McFly complies, an amused Rizzi compliments him on his "generosity"âwhile Fox may have been deeply in debt, Mrs. Sheridan's estate is so vast, Sarah will still emerge an extremely wealthy woman. She informs McFly that she will marry him and hand over the money once he resumes his law studies and becomes a lawyer.
question: What is the name of the mistress who visits Cecil Fox at his "deathbed" who is known to be a Texas hypochondriac?
answer: Mrs. Lone Star Crockett Sheridan