In the very wealthy, inheritances are not distributed equally amonng all heirs, as is common among us peasants.
Generally, the bulk of the estate goes to one, with a pittance given to the others, just enough to keep them happy.
Though that's not always the case, the Pritzker family case in point. There's still war going on among all the children, grandchildren, neices and nephews for the estate of Abram Pritzker.
But your idea does have some merit, there are a few instances in history of mysterious disappearances/deaths of heirs, and sometimes institutionalization of troublemakers.