U.S. private equity funds Blackstone Group LP and Carlyle Group LP are pushing ahead with plans to establish so-called passporting rights in Luxembourg to retain the ability to do business in the European Union after the U.K.’s exit, according to people familiar with the matter. The move is seen as administrative, less about moving people and offices and more to preserve access to European investors after Brexit, the people said, asking not to be identified because the plans are private.