When I sold my '15, I just emailed Joyce with the buyer's name, phone and email, and she made it work. Buyer must fill out an Entegra form which CS sent after my notification.
Stew and Diane (and Marco)
2018 Entegra Cornerstone 45X
Formerly: 2015 Entegra Cornerstone 45B, 2013 Entegra Aspire DEQ IFS, 2004 DSDP; all sold