Why were sixteen people asked to go to the south library of the westing mansion in the westing game?

In "The Westing Game," sixteen people were invited to the South Library of the Westing Mansion to participate in the reading of Sam Westing's will. Each of these individuals was an heir or had a connection to Westing, and the reading was intended to reveal the terms of his will and the challenge they would face to inherit his fortune. The gathering sets off a complex game filled with intrigue, alliances, and mysteries as they seek to claim their share of Westing's estate.