Some additional details here (without a paywall), too:
https://yourmileagemayvary.net/2022/...oarding-order/
For a week in mid-December, families traveling together will be offered the opportunity to board before those who hold an A-list boarding assignment. However, those families would be required to sit behind row 15. As per vice president of business transformation Angela Marano at Southwest’s Media Day last week, the experiment is scheduled to occur during mid-December, at four of the airline’s gates at Hartsfield-Jackson Atlanta International Airport (ATL).
Interesting - the wording makes it sound like it would be after A1-A15 but before A15-A30, which I think gets ahead of those on BS fares whining and continues to offer good monetization opportunities for Upgraded Boarding for WN.