Use the Swap TIN Edge interactive tool 
to interactively connect two opposing nodes to form an alternate pair of triangles. Click the triangle edge to change its direction.
Swapping an edge requires the TIN to use constrained triangulation, which cannot be undone once the TIN is saved.
- Click the TIN Editing drop-down menu and click Start Editing TIN.
- Click the Swap TIN Edge button on the TIN Editing toolbar. A graphic line displays and snaps to the closest valid triangle edge relative to the cursor's current position on the TIN surface. This helps to visually ensure the connection is what you want before you actually click and commit the action.
- To change the direction of the triangle edge, click the desired highlighted edge.