Two members of the Sackler family have agreed to make a rare public appearance to take questions from a congressional committee that is investigating the role of the company they own, Purdue Pharma, in fueling the nation’s opioid epidemic. The agreement to appear Thursday headed off the possibility of the U.S. House Oversight Committee issuing subpoenas. The committee is likely to have questions about Stamford-based Purdue’s settlement with the U.S. Justice Department last month. While the OxyContin maker faces penalties and forfeitures totaling more than $8 billion, no individuals admitted to crimes.