Sister in open marriage takes sharing too far

Chicago Sun Times: Dear Abby: My daughters are attractive young women, both doing well in their professional careers. “Melanie,” who is 27, is married to “Sam,” an extremely attractive and successful man. My 30-year-old daughter, “Alicia,” has been divorced for a year. Her marriage failed two years ago because she and her husband had an appetite for sex outside their marriage. While I was disturbed about that, I was horrified to learn that Melanie allows her sister to occasionally have sex with Sam . . .