From the tree "view' click on the person who's relationship you want to change to open their profile. I that window you click on the "MORE" button which gives you an options menu and you want to click on the "move" button - this will put a icon in the corner of your screen which you have to drag to the person you want to link together. (you can't break a relationship until you make an alternate relationship) This is so complicated that I delete people and reenter them- failing that, just change the identity of the child entry.
