Cousinology: Heirs to Mary J Walker of NYC

While checking Binghamton, NY newspapers for items regarding the Clark family there I came across a page 1 headline:

     BINGHAMTON PEOPLE HEIRS TO NINETY THOUSAND DOLLARS

And that was in 1902! Named were Arthur W. Clark, Mrs Frances Gordon Sears, and Charlotte Haynes Higbee as "children of her cousins".  There is lots of intrigue here. 

Who was Mary J. Walker that she had an estate valued at a million dollars, who were the three cousins, and how exactly were they related

Cousinology: Charlotte Higley in Binghamton 1910

While piecing together the descendants of Dr. Adam Clark and wife Harriet Watson, an unrecognized “niece” showed up in the 1910 census with Harriet Gordon Clark, widow of their son Henry.