Creo Interactive Surface Design (Style) > Connections > Curve Connections > Endpoints for Curve Connections
  
Endpoints for Curve Connections
The following rules apply to endpoint selection when you create connections between two curves or connections between a curve and a surface.
Connections between Two Curves
To create a Tangent connection between curves, the endpoint of the follower must be a soft point on the leader.
Connections between a Curve and a Surface
Connection
Endpoint Rule
G1 - Surface Tangent
G2 - Surface Curvature
G3 - Surface Acceleration
Must be a soft point to a surface, a surface boundary, or a COS
Draft Tangent with a planar reference
Must be a soft point to any other curve
Draft Tangent with a surface reference
Must be a soft point on the surface boundary or a COS