I've tried to search online to see whether it is allowed to apply for more than one visa at a time. For example, I am waiting for various factors to eventually obtain a TN Visa. I might apply for the K1 Visa in case it is quicker than obtaining everything I need for my TN. If I apply for a K1 visa, and if during the process the opportunity for the TN visa presents itself, can I then withdraw my K1 application and go with the TN?