Add a corner
What this editing action does is that TAD would create a new corner between the first and second helper. Now that a new corner was created; you will find the helpers would be relocated to the new edge that got created in the process.
Warning: If you happen to have the architect exactly on the first helper, you may wonder where the additional corner was created. Answer: It got created alright, but happened to be exactly on the previous helper. So make sure that the architect is moved away from the first helper before you invoke this command
Don't worry if you accidentally created a new corner erroneously. You can press UNDO and get the earlier shape of the object back. You can also delete the new corner that you wrongly created.
Press F1 inside the application to read context-sensitive help directly in the application itself