Not operatic, but Lucy Simon is/was a singer too and once put out a solo album of her own. Unfortunately for her, this was during Carly's heyday and it was widely ignored which - according to an interview I read (in a book on sibling rivalry, not a music publication) - caused her huge pain. Apparently even her own mother and father were dismissively indifferent to her record, though this info comes from Lucy herself who is of course a less-than-objective source. But years ago I saw an excellent interview of Carly in an ancient issue of (?)Rolling Stone which indicates the same sort of feeling, of having had distant and judgmental parents, even though the family were materially well off (Dad is Simon of Simon & Schuster publishers). Both sisters sure seem to have paid high dues in the emotional vulnerability department.