To add task assignees open the task by clicking on the task subject while the tasks are listed.
On the right side of the task modal, there will be a dropdown to select assignees.
You can add an unlimited number of assignees to specific tasks and track their time logged.
After you add a member as assigned to the task this member will get a notification email and built-in that is assigned to this specific task.
When the task is related to the project only project members will be shown in the dropdown while selecting members as assignees.
