@Meysam_Ghorbani
Generating a curve for port milling is not something that PowerMill could handle....cleanly. you may be able to create a spline, but this would be more of a manual process and would not be very accurate. This may create some unwanted results.
The best method would be to bring the geometry into surface Modelling and create the curve there since the curve creation tools are more robust there. For port milling, I'd start with a spine wireframe from the port surfaces.
Here is a quick demo....
https://help.autodesk.com/view/PWRS/2020/ENU/?caas=caas/sfdcarticles/sfdcarticles/How-to-create-a-sp...
Christopher Marion
Technical Specialist - CAM
SolidCAD - Canada