@feierfeilgreg
Your question can be interpreted two ways. It's not clear if that means you want to prepare a different online return for another person, or if for some reason, you want to redo a return you already prepared. The answer would be quite different if it's your own return you want to redo--especially if it has already been filed. So my answer in my first comment above assumed you want to prepare a second return for a different filer. If that's not the case, then you need to provide more detail so it becomes clear what you are wanting to do.
