How did Dr. Shaw know that Walter was pretending to be David's spoiler?

It turns out that Dr. Shaw and Walter have an agreement to build a lake house. After Flanland died, the woman cried at the hologram. It was agreed that they would build a lake house, but later Walter said that I would help you build it. In the film, the hostess asked Walter before going to bed: When I wake up, can you help me build that hut? David looked "I can't answer what you are saying", and the hostess realized that Walter pretended to be David.

Alien: The Contract is an American sci-fi film produced by Fox Company in 20th century, which was directed by Ridley Scott and starred by Michael Fassbender, katherine waterston, billy crudup, Danny McBride, Demián Bichir, carmen ejogo, Amy Semez and Nathaniel Dean. This film is the sequel to the 20 12 movie Prometheus, and the second prequel trilogy of Alien series.

Introduction:

The timeline of Alien: Contract is set at 10 years after the end of Prometheus' story. The spaceship "Contract" carrying immigrants encountered an accident during its voyage and landed on a distant planet.

And found the survivors of Prometheus, biochemical David, and terrible alien monsters waiting for them. This seemingly paradise planet is actually a doomed hell.