How were all the heirs related to Sam Westing?

Sam W. Westing was all there uncle.

The answer above is incorrect! The only biological relationship with Sam Westing, born Sam Windkloppel, is Grace Windkloppel-Wexler, and her 2 daughters, Angela and "Turtle" Wexler. Sam is their uncle and great uncle, respectively. Berthe Erica Crow was Sam Westing's former wife. Alexander "Sandy" McSouthers and Sam Westing are both one in the same person. All other heirs have no biological relationship with Sam Westing at all, but merely had touched Sam Westing's life in the past directly and/or indirectly one way or another.