Reparam Curve Restrictions
To add a reparameterization curve to a surface, the surface must contain more than one curve in a given direction, as in a loft surface or a boundary surface. You can add any number of reparameterization curves in the U direction and in the V direction. The use of reparameterization curves is limited in the following cases:
Surface Type
You can only add reparameterization curves in one direction.
Trimmed Rectangle
You cannot add reparameterization curves.
You can add reparameterization curves only between two or more internal curves.
Make sure that reparameterization curves in the same direction do not cross each other or any internal curves. The rules for dragging internal curves apply to dragging reparameterization curves.