S03E32: The Brewsters Return

The Brewsters come to Beverly Hills to build their new home on a vacant lot they purchased, and they request the Clampetts don't learn of this. But the Clampetts are planning to move back home to the Hills. When they tell Drysdale, he reveals the secret. Drysdale tells Brewster what he has done, but explains it was to save the Clampett oil account, and because of this, he has to visit the Clampetts.