My experience matches all the others in that changing a transit to a stopover has always constituted a reroute and hence a reissue. That has been the case for the 10 years or so that I have been using OneWorld Explorers, using multiple issuing anr reissuing airlines. Having said that I have only done this on paper tickets where the ticket needs to be reprinted showing the changed information. My current AONE3 is the first time I have failed to avoid eticketing and the situation hasn't arisen on that one.