At Facebook’s new Calibra subsidiary, the group’s leader, David Marcus, relies on a mix of Facebook veterans and people from his Silicon Valley past to figure out how to weave the Libra digital currency into the social media giant’s family of apps. Of the eight people who report directly to him, two used to work at PayPal, where Mr. Marcus was previously president, while others worked on Facebook products like Instagram and the News Feed.

Together, the group—whose leadership team is shown in the chart accompanying this story—oversees one of Facebook’s most important and complicated new initiatives in years. Calibra is the roughly 100-person organization charged with creating a digital wallet app for Libra, the new digital currency also created by Facebook, along with integrating it into Messenger and WhatsApp as a payment system. It is not to be confused with the Libra Association, the Geneva, Switzerland–based independent consortium that will govern the digital currency and which Facebook says will eventually be composed of 100 member companies, including itself.