The other giant sad factor in the Osmond family's lives is the fact that their father George badly mismanaged their income, which was substantial. It is likely the reason Donny and Marie spent what should have been happy retirement years working a long-term act in Vegas– to replenish the family's financial assets.
Another sad side note: parents George and Olive Osmond originally came up with the idea of having the five younger brothers become a performing act as a way of financing the educations of the two oldest brothers, who were both born deaf. The eldest of the "Osmond Brothers", Alan, is disabled with multiple sclerosis today. Separately, after ALL those years of performing onstage, Donny won the lead role in "Joseph and the Technicolor Dreamcoat" on Broadway, and was hit with a surprise case of severe stage fright. His wife Debbie and his doctors helped him through it.
My big sister was a verbose, walking encyclopedia of Osmond Brothers facts back in the day. There was no avoiding Osmond trivia in my house.