Yes, there are a few different ways of selecting multiple curves as boundaries depending on what you want to do.
First, when the Boundaries Selection Method is set to Curves, look into the different Curve Rules in the Top Border Bar.
The Tangent Curves and Connected Curves options are usually popular choices.
However, users don't always want to select an entire chain of curves that are tangent or connected. There is another method to select the beginning and end of a chain and automatically get all the curves in between.
To do this you must first have your Selection Method set to Curves as before. Next, select the More icon next to the Curve Rule menu, which looks like a little arrow.
When the Options dialog opens, check the Chain Between box and select Close.
Upon exiting the Options dialog you will notice that the Curve Rule has automatically been set to Connected. Now you can select just two curves along a chain and NX will fill in all the rest between. The key is to select the curves at at the ends pointing toward each other.
I am sorry my question is not clear, this is not what I am looking for,
what I want is to select non-connected multiple curves from 3D profile or planar mill operation
using open curves option. When I select a non-connected multiple curves it automatically connect all the curves.
Is there no option that I can select all the non-connected curves then automatically populate all the curves under the list of curves dialog box. Now I select non-connected curves by clicking the add new set button, but mostly I have hundres of curves to select. I am also aware of the fixed contour operation with curve/point drive method, there I can select multiple non-connected curves at once but I cannot make extended tool path.