A pose file containing the jp's from the legs cr2 would fix that right up. All you'd have to do then is click on the file and it would give the pants the same jp's as the legs. A pose file containing joint parameters is a very simply thing to make. You just take everything out of the cr2 except the channel information, such as twistY, taperX, zOffset, etc and save the file as a pz2 instead of cr2. I've made a number of these for converting clothing between all the major characters. Perhaps you could suggest this to Umutov?