I agree that you need a deed to add someone to title. The next issue is what kind of deed and what kind of title do you want to have, and that depends on what you are trying to achieve. Are you doing this for estate planning purposes only? Then you should talk with an attorney about doing a beneficiary deed. Are you doing this to actively co-own property with a relative now? If so, then you need to likely have a special warranty deed done. You also need to decide whether or not you want to hold title with this relative as tenants in common or joint tenants. A consultation with a real estate attorney can make sure you are pointed in the right direction for what you want to achieve.
Disclaimer: This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. I am licensed in Arizona and can only provide general comments on matters outside of Arizona law. Actual legal advice can only be provided after a direct consultation in which all of the relevant facts are considered before providing a response.
You need to execute a deed; preferably a warranty deed, and file it with the Recorder's office.
Douglas Edmunds is in the business of helping people and companies file for bankruptcy protection. The bankruptcy code requires that I call my firm a "debt relief agency." Any answers or information provided is for general information purposes only and is not intended to be a legal opinion, legal advice or a complete discussion of the legal issues. This is not intended to create a attorney-client relationship. Each individual's situation is different and you should seek independent legal advice from an attorney familiar with the laws of your state for specific information.