Creo Simulate > Reference Links > Add for Interpolation
  
Add for Interpolation
Use this button to add a new interpolation point.
As you select each point, Creo Simulate:
allows you to select up to four points
marks each location you select with an X
sequentially numbers the interpolation points
displays an entry box on the dialog box in which you can enter a value for the point
Return to Load Interpolation or Interpolation Over Entity.