"They had done essentially no estate planning prior to his death. The notion that he would die at such a young age was really never considered," Shilo says. "I would say it took a year to a year-and-a-half before she felt things were under control."

Shilo had another client with a substantial tech-based fortune who was diagnosed with terminal cancer while he was in his mid-40s. They had a year and a half to put his financial affairs in order. Knowing his wife's habits, he put spendthrift provisions in place so that his estate wouldn't be spent down too quickly. Although the precautions were instrumental in keeping the estate intact, his widow is living a much different lifestyle than she did when her husband was alive, and it's been a constant struggle for the trustees to deal with all of the additional requests for money.

"Fast forward seven years, and this woman has since [been dating] an artist and has spent a large portion of her husband's estate," Shilo says. "We had contemplated that, but we really didn't think it would happen."

Advisors try to anticipate the worst that can happen, but it's impossible to accurately predict how surviving spouses will live their lives or what their children will do. Shilo says that while her firm has helped numerous clients face difficult and unexpected situations, sometimes the clouds do have silver linings. "The children pull together in ways you never thought they would, and they become a much more close-knit family," Shilo says. "Things can happen unexpectedly in good ways as well."