A person who makes a will (a testator) may update or revise the will at any time during their lifetime if the testator has the required mental capacity (is of sound mind) and the document is executed or signed with the required formalities (such as witnesses and signatures), as provided by the state’s laws.

There are generally two ways to update a will—execute a new will (usually the best option) with the required witnesses, signatures, and other formalities—or execute a codicil (a supplement to an earlier will), with the required witnesses, signatures, and other formalities, as provided by the state’s laws.

Laws regarding the use of codicils and the required formalities for wills and codicils vary from state to state and are usually located in a state’s statutes—often in the estates code or probate code.

A testator who updates their will by executing a new will should usually destroy the previous will to avoid questions regarding which will reflects the testator’s true intent and to avoid competing wills being offered for probate (recognition by the court).

In Oklahoma, a testator has the right to update or revise their will at any time as long as they have the mental capacity to do so and adhere to the state's legal formalities. To execute a new will or a codicil (an amendment to an existing will), the testator must follow specific requirements, including having the document witnessed and properly signed. Oklahoma law typically requires the presence of two disinterested witnesses for the execution of a will or codicil. These formalities are outlined in the Oklahoma statutes, particularly in the sections dealing with estate planning and probate. When a testator chooses to execute a new will, it is advisable to destroy any previous versions to prevent confusion and ensure that the most recent will is recognized as the true expression of their wishes. If there are multiple wills, it could lead to disputes during the probate process, where the court determines the validity of the will.