JavaScript must be enabled in order to use this site.Please enable JavaScript in your browser and refresh the page. To Combine Two B-spline Surfaces (Sharing a Common Edge) Select the Combine Surfaces tool ( Modeling > Surfaces > Modify Surfaces > Stitch/Combine > Combine Surfaces ). Select the first B-spline surface. Select the second B-spline surface. Enter a data point. Parent topic: Combine Surfaces tool