Similar to Phases and Subphases, we also have custom Milestones. You can name your Milestone that is only related to this project instead of using the standard Milestones.
To add a new standard phase/milestone that will be available for all projects, click Manage Standard Phases/Milestones at the bottom of the list.
Only Admins have access to Standard Phases/Milestones page in the organization settings.Enter the title of the Milestone. Select a parent to place it under a Phase/Subphase, then click "Create."
The Milestone will show at the bottom.