As far as I've ever seen when I add a control like a textbox, InfoPath automatically adds a field (with a generic name like "field1", "field3" etc) to the main data source. I don't think it is possible to add an unbound text box? If it was, I wouldn't do it - binding is where the control stores its data, so there would be no point. You can add fields to the main data source w/out putting corresponding controls on the form, and I do that all the time. :)
Hilary Stoupa
