my limited experience with open jaws [ i've done a few], is that the open jaw must be shorter than either of the other 2 legs....this presents a problem with cruises between europe and the us, for example, when you don't want to use the cruise line's air....this has happened to us a few times and i have been forced to use awards or illeagle [against policy] routings [like not using the return leg of a rt].