I also recommend sticking with same UY so you don't have to transfer points. It can be a pain since you have to call in to transfer and call in to book with transferred points. If trying to grab something right at 8am of 7 month window, it may be gone by 9am when you call. Also cannot transfer banked or borrowed points ans cannot borrow transferred points. Can only bank transferred points. We have two UY and are always in borrow mode and sometimes cannot book what we want because we need to transfer (say we want to add a night to Oct 2018 trip and it's 22 points and we have 10 in June UY and 12 Aug UY but all are 2019 points) and borrow...which can't be done. Hope I am not confusing you. Just easiest to have one UY. Then you have a dtop down when booking and can select what you want to use.