You can edit milestones and steps used for calculating earned value.
To edit milestones and steps:
On the Navigation menu, click Workflows ยป Change Management.
In the List View, select the change request.
On the General Tab of the Change Request Form, click the Change Details button.
In the Change Details View, click the Milestones/Steps tab.
In the Milestones grid, select and edit the milestones or steps.
The baseline and forecast finish dates of the milestone cannot be greater than the baseline and forecast finish dates of the work package.