Derived Curve command
Use the Derived Curve command 
 to construct a new curve that is derived from one or more input curves or edges.               If all the input curves or edges are connected at their endpoints, you can specify               that the derived curve is constructed as a single b-spline curve. If the input curves               are connected, but not tangent, the output curve will have a minimal amount of curvature               added so that a single, smooth b-spline curve is constructed.
You can construct a single derived curve from multiple bodies. For example, you can construct a derived curve from a sketch (1), edges on a construction surface (2), and edges on a solid (3).

© 2021 UDS