A proximity breakline does not add new points to a surface. Instead, the nearest surface point to each breakline endpoint is used. The triangles that make up a surface are then recomputed making sure those points are connected. A proximity breakline is created using the same fashion as standard breaklines except you call AeccSurfaceBreaklines.AddProximityBreakline instead of AeccSurfaceBreaklines.AddStandardBreakline.
Set oBreakline = oTinSurface.Breaklines.AddProximityBreakline( _ oEntityArray, _ "Sample Proximity Break", _ 1#)