dNodeDataForKey(parentkey);
        if (parent !== null) {
          if (n.bounds.intersectsRect(viewb)) {
            // N is inside viewport
            model.addNodeData(parent); // so that link to parent appears
            const child = diagram.findNodeForData(n);
            if (child !== null) {
              const link = child.findTreeParentLink();
              if (link !== null) {
                // do this now to avoid delayed routing outside of transaction
                link.fromNode.ensureBou