For Greta Harrington and her husband Robert, it was love at first sight. The two were married for 52 years until cancer took her husband at the age...

For Greta Harrington and her husband Robert, it was love at first sight. The two were married for 52 years until cancer took her husband at the age of 84. Greta is currently 83 years old, and her marriage produced three offspring: Samuel, 50 years old; Katherine, 45 years old; and Benjamin, 40 years old. In his will, Robert left all of his financial interests, a considerable sum valued at $5 million, entirely to his wife; in his will, he also expressed love and affection for his three children, as well as the desire that Greta devise the remainder of the couple's estate to their children, in equal portions, upon her death.

Greta has recently been "keeping company" with Gary Watson, a twice-divorced, 65-year-old bachelor with a reputation for "womanizing." While visiting her mother one weekend, Katherine is shocked to see a fully-executed will on the desk in the living room, devising all of her mother's estate to Gary Watson. She immediately calls Samuel and Benjamin, schedules an emergency "sibling meeting" for Sunday, and wonders what to do about her mother's ill-advised decision. She has noticed in recent months that her mother is often forgetful, frequently calls her "Sharon" (her aunt's name,) and often confuses the days of the week.

Do the children have any legal rights in terms of successfully invalidating Greta Harrington's will? From a legal and/or ethical standpoint, should a mother (even of adult children) be allowed to "disinherit" her offspring?