The problem you need to solve: Work should be logged for a user but he isn't able to log it right now. How Minyaa solves this problem: Minyaa allows you to grant a user the privilege to log time for another user.
Allowing a User to Log Work by Delegation
In order to allow a user or a group to log work for other users, you have to grant them the Edit Worklogs for Team Members permission. For more information on permission management in JIRA, please see JIRA: Managing Project Permissions
