Redmine

Hi!
I'm looking for a way to update time tracks of my team members, who report by any means of report, except redmine (i.e. verbally, snail mail, skype,...)

Is there way to do it (track times on behalf of smb.) in a SIMPLE way, not just by logging out and logging in with different user name?
(suppose, this option should be granted only to task creator or manager)

Yours,
Alexey

P.S. I have several teams, half of them track their times using redmine, and others - just saying me what they did recently.