The settlement over Ashley Madison’s data breach presents a unique conundrum: How do you find class members who don’t exactly want to be found?

From the start, anonymity has plagued lawsuits over the 2015 hack that compromised the personal information of 37 million subscribers to AshleyMadison.com, an online dating site that targets people looking to have an affair. Many class action attorneys, questioning who would want to be identified as a plaintiff, bowed out of the litigation. Those who pursued cases asked a federal judge in Missouri to allow their clients to use pseudonyms, but they weren’t successful.