Assumptions can be very dangerous when it comes to estate planning. You definitely want to have open lines of communication with your heirs. Talk about your plans, their desires, and what legal steps you're going to take to officially put everything in place. Talking it out in advance can help to avoid issues in the future.
One assumption that people often make is that leaving property to an heir is a gift, something they'll be happy to take on. However, assets may come with responsibilities. They may not actually want those responsibilities.