It would be great if that was a feature, but, I haven't found it.  My work-a-round is to create my own PDF copy of the tax return, water marked review copy, of just the forms in the actual return.  Then, I make a PDF copy of items in the return that I do not want to be watermarked, such as ES and the client letter.  I then upload both of those as "other documents".  I check the box that I do not want DocuSign to automatically add a watermarked copy of the return to the envelope.

I would be really interested to find out if there are settings that would make this automatic.  Nothing is more frustrating than having to re-invent the wheel for something that could be automated.