Shortly after the display name update, I could add players by their original username, and my friends list would automatically show the new name. Similarly, if I enteir their old usernames on the hiscores, the display names would be shown instead. However, it seems that I can no longer do so. For example, I have a friend whose original username was Sarah_Devil0 but has changed it since then. Now, when I tried adding her, I get a message saying that the player does not exist. Adding her current display name works, though.

 

So is it no longer possible to add players by their original nams if they had changed it a long time ago? If so, is there a way to find out someone's current character name by knowing only their old one?

I don't remember the exact length of time but I think after a month or two it stops being possible to add someone by their original username as the name becomes freed up for other people to use. As far as I know there is no way of finding out what someone's current name is with only their old one unless you have them added and even then you can only see what their last name was.

Actually, it becomes impossible when a user takes a third name.

 

If you were to change your name once, the original name will still be available after a year. There doesn't seem to be a limit to that time, but when you change it from the second to a third name, the first becomes available again.