This question is NOT just a hypothetical. Missionaries in Africa asked me to answer this and I don't think it's application will be limited to them for too long. It seems to me that the moral slip-slide of our culture is heading toward a time when more and more of us will be confronted with the topic of polygamy. This is one of my final videos in the series I have done on divorce and remarriage. Here's the playlist with all those videos. https://www.youtube.com/playlist?list=PLZ3iRMLYFlHtBvJzugPJp9P5X1T-hA91j