It is always better to head problems off in advance. Ensure your wishes are carried out if the worst should come to pass. Have a legal Will drafted by an attorney. Sign up to start your estate planning.
If you like, you can have certain provisions put into a Will as well. For example, you might want to pass on a sum of money to your grandchild when they turn 18 years old. That money would not have a clear purpose without a Will, and might be passed on to other family members, never seeing your grandchild.