Its not allowed. Period. This is not giving permission to another persons claim. This is giving permission to another persons account. I'm not going to do entire investigations as to who, what, where, and why passwords were given, when people were allowed to use it, when they were not etc. etc. If so and so said that steve could use it but only on sundays and then steve gives it to frank who gets the character killed and frank was not allowed to use it etc.
If you share your password, AND if you log into another players account who has given you their password, ALL parties are running the risk of a ban if/when the other party cries foul.
There is no good reason for it. Don't do it. Make your own alt account if you want an alt.
EULA wrote:
E. End User agrees to take appropriate measures to ensure the safety
of its account in the Game and passwords and to prevent
unauthorized use of these by a third party. If End User has reason
to believe that third parties have obtained such information or can
obtain it, the End User shall immediately inform Mortal Moments Inc. and
change its data. Unauthorized access by any third parties to End
User’s personal information, account and in-game currency account
in the Game is strictly forbidden. End User agrees and acknowledges
that he/she shall not sell, give or transfer its account, in-game
currency account or personal information to any third parties.