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

She was Mary J Watson (1832-1902), the childless widow of Evan T. Walker, and one of two daughters of John Watson, a wealthy leather tanner/manufacturer who died in New Jersey in 1891.  

But how she was related to the 3 named heirs? Mary's father, John Watson, had numerous siblings including oldest sister Harriet, who married Dr Adam Clark. Harriet and Adam were Mary's aunt and uncle-- the three named heirs were their grandchildren. 

Their son Henry Clark (Mary's cousin) was the father of Frances (who married Dr Frank Sears) and Arthur. Henry's sister Eliza and her husband Henry Higbee were parents of Charlotte. Following Eliza's death, Charlotte had moved from NYC to Binghamton and lived with Frances and Arthur.

These "cousin" notations can link families that would otherwise never be recognized as related.