You can bridge two neighbour curves using Bridge Curve.
To bridge two curves:
Click Bridge Curve (Curve toolbar) or click Geometry, Curve, Bridge Curve .
To bridge two curves naturally, select two curves and define the module length of the tangent directions properly. If two selected edges lay on the same surface, you can check "Same Surface" to constrain the new bridge curve on the surface. If you want the bridge curve's tangent module length is the same as the selected curve, check "Native Tan Module".
a. Bridge two curves on the same surface. Check "Same Surface". b. Using the bridge curve to replace one edge on the surface (See Heal Model, Edge, Replace)
You can also create a bridge curve by selecting four points. .
Bridge curve by 4 points.