Whenever users need to take some time off (e.g. vacation), administrators need to move issues to different users that may require extra permission changes as well which will be kept in place only for a small amount of time.

It would be great if JIRA had a feature to add an user as a replacement for another user in a project.
This replacement would automatically have all of the user's permissions added to him as well as his tickets (assigned,reported and watched).

Other suggestions

• Assignee field apart from the person who is in charge of the issue, also the substitution (in brackets or something similar)
• In the list of watchers the substitution might be visible
• If an issue is set to the absent person, then there might be some message informing about setting also substitution
• "replacement" user might be able to receive all notifications which normally are addressed to the absent person (as reporter, assignee and watcher)
• also if there is any comment addressed to the absent person "replacement" user should be notified