My goal is to distinguish between old and new users. I would like old users to have usernames with fewer than 4 characters, while new users should not have usernames shorter than 4 characters. In other words, I want to set the minimum username length for new user registrations to 4, while ensuring that existing users can retain usernames with a minimum length of 3.Could anyone please advise me on how to achieve this? Thank you for your help!