In Taverna 2.x, you can add a workflow as a nested workflow by selecting Insert -> Nested Workflow from the top menu or right-clicking on the white space in the Workflow Diagram. Alternatively, you can merge a workflow with the current one by selecting Merge workflow from the Insert menu.
We recommend that you add a workflow as a nested workflow. This preserves the modularity and makes reuse and repurposing much easier. Credit and attribution of the original author are also clearer when you add another workflow this way.
In Taverna 1.7.x, you can import a workflow from File -> Import workflow into an existing workflow to effectively merge the two. To add nested workflow to your workflow click the Add nested workflow button in the Advanced Model Explorer.
