how to respond to divorce papers from another state

Well, the answer to the question you asked is probably "no," because you really should file a response, but the place to file it is in Montana, from what you have written.  Assuming Montana has jurisdiction over all issues involved in the case (your facts are too scanty to tell; if you want to see what the rules are, subject by subject, see the article "The Basics of Family Law Jurisdiction," posted at http://www.willicklawgroup.com/published-works/ about mid-way down the page), you need counsel there. My guess is that you should confer with an attorney in Montana; if you don't have one, consider starting your search at http://aaml.org/members/montana.  If you conclude that Nevada has jurisdiction over anything relevant, consider calling my office or that of another family law specialist.  Good luck.