You can place a guest name on internally banked weeks with Westgate..
However, make sure you fully understand what your costs would be before you offer a week to a guest.. I've never seen anything in writing explaining how upcharges are billed, but almost everytime I've made a request for an exchange there are some mysterious additional charges that are required (they either say it is a resort upgrade, a unit upgrade, a season upgrade...). Also, be sure to specify which banked week you want to use.. They won't automatically use the oldest unless you request it.
When dealing with this.. Proceed with caution and keep one hand on your wallet at all times..