You can select more than one item at once. Hold down
the Ctrl key to select multiple individual items or hold
down the ⇧ Shift key to select adjacent items on the
list.
Result:The Select Users dialog is closed and the selected
user or users are added to the Substitute users
list.
Click OK to close the Substitute
Users dialog.
The users who you have just appointed as your substitute users will now be able to
complete assignments assigned to you and will receive notifications about such
assignments.