Within Teamwork Projects, you can associate a task list with an individual milestone.
To link a milestone, go to the Tasks area of your project. Hover over the name of the relevant task list and choose the Edit option.
In the pop-up modal, select the Milestone tab. You can then choose an existing milestone from the dropdown, or create a new one.
Click Save Change to add the milestone to the task list. It will appear below the task list name.
Note: Any tasks in the task list that do not have their own due date set will automatically inherit the due date of the milestone.
For more information, see: Adding a milestone